Skip to content

Latest commit

 

History

History
3092 lines (2083 loc) · 55.2 KB

Tutorial.md

File metadata and controls

3092 lines (2083 loc) · 55.2 KB
Raw

C++ Basic Tutorial

Note:

  • This Tutorial is mainly Practical.
  • Give a STAR if you like this
  • FORK to get more update
  • Make a PULL REQUEST to countribute

Put your phone in desktop mode for easy access


Syntax of C++ Language

  • iostream

    1. It stands for input output stream
    2. It is a collection of predefined functions/methods
    3. It is also called library of C++

  • include

    1. To include the header file into the program

  • #

    1. It is called preprocessor
    2. It includes the library of C++ into the program before the execution of program

  • conio

    1. It stsands for console input output
    2. It is used to show the ouput on console window

  • void

    1. It is a keyword
    2. It indicate that no one value is being returned by the function
    3. If we use anyother keyword like int, float, char etc in place of void then we will use return keyword

  • main

    1. It is the function which is called the entry point of any program
    2. The execution of any program starts from the main function
    3. If in a program there is only one function then it should be main function

  • clrscr

    1. It stands for clear screen
    2. It is a predefined function which is used to clear the output screen
    3. It acts like a duster on output screen
    4. It is define in the conio.h header file

  • cout

    1. It is a keyword which is used to print data or information on the output screen
    2. It is always use with insertion operator
    3. cout (pronounced "see-out")

  • getch

    1. It is a predefine function which is used to hold the output screen
    2. It acts like a duster on the output screen
    3. It is define in the conio.h header file

  • Remember:

    • The compiler ignores white spaces. However, multiple lines makes the code more readable.
    • Every C++ statement ends with a semicolon (;)
Comments in C++
  • Definition
    • Comments can be used to explain C++ code, and to make it more readable.
    • It can also be used to prevent execution when testing alternative code.
    • Comments can be singled-lined or multi-lined.

  1. Single-line comments start with two forward slashes (//).

    
   // This is a comment
  cout << "Hello World!";

   ```

  2. Multi-line comments start with /* and ends with */.

    
  /* The code below will print the words Hello World!
  to the screen, and it is amazing */
  cout << "Hello World!";
Variables in C++
  • Variables

    • Definition

      1. It is a name of storage space which is used to store data
      2. It's value is changable
      3. It always contains last value stored to it
      4. It's always declare with data type

    • In C++, there are different types of variables (defined with different keywords), for example:

      • int - stores integers (whole numbers), without decimals, such as 123 or -123
      • double - stores floating point numbers, with decimals, such as 19.99 or -19.99
      • char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes
      • string - stores text, such as "Hello World". String values are surrounded by double quotes
      • bool - stores values with two states: true or false

    • Varable Declaration

      	int rollno;
	float marks;
	char grade;

      Here:

      • rollno is a variable of type int
      • marks is a variable of type float
      • grade is a variable of type char

    • Variable Initialization

      	int rollno=201
	float marks=85.6
	char grade='A'

      Here:

      • 201 is the value of rollno
      • 85.6 is the value of marks
      • A is the value of grade (Character value is always written in single quotes)

    • Rules to declare a variable

      1. The first letter of a variable should be alphabet or underscore(_)
      2. The first letter of a variable should not be digit
      3. After first character it may be combination of alphabets and digits
      4. Blank space are not allowed in variable name
      5. Variable name should not be a keyword

    • To create a variable, specify the type and assign it a value:

      type variableName = value;

      Note: Where type is one of C++ types (such as int), and variableName is the name of the variable (such as x or myName). The equal sign is used to assign values to the variable.

       **Example 1**

 Create a variable called x of type int and assign it the value 15:
 ```
 #include <iostream>
 using namespace std;

 int main() {
 	int myNum = 15;
 	cout << myNum;
 	return 0;
 }

 ```
  • Constant in C++

    • Definition

      1. An elemnt of program whose value can not be changed at the time of execution of program is called constant
      2. It is also called 'literals'
      3. It may be int, float and char data type

    • Rules for constructing integer constant

      1. It must have atleast one digit
      2. It must not have a decimal point
      3. It may be positive (+ve) or negative (-ve)
      4. The range of integer constant is between -32768 to +32767
      5. No comma or blank sppace are allowed in integer constant

    • Rules for constructing floating constant

      1. It must have atleast one digit
      2. It must not have a decimal point
      3. It may be positive or negative
      4. No comma or blank sppace are allowed in floating constant

    • Rules for constructing character constant

      1. It is a single alphabet, digit, or special symbol
      2. The length of character constant is 1 character
      3. Charcter constant is enclosed within single quotes (Example: char c='A';)

    • Use of constant in program There are two way of using constants in the C/C++ program

      • Using const
      • Using #define
  • Storage Classes in C++

    • Definition A storage classes in C++ defines the scope, lifetime, default initial value and storage space of a variable.

      There are four storage classes in C++:

      1. automatic
      2. static
      3. register
      4. external

      • automatic:storage class

        1. Automatic variables are declared inside a function in which they havae to used
        2. When the function is called automatic variables are created and destroy when function is exited
        3. Automatic variables can nt be used outside that function in which its declared. It means w can say that it is private member
        4. Automatic variables are also known as local variable
        5. auto keyword is usd to declare automatic ttype variable


      • Example

         #include<iostream>
 using namespace std;
 int main()
 {
 	auto int x=5;
 	{
 		auto int x=3;
 		{
 			auto x=1;
 			cout<<x<<end1;
 		}
 		cout<<x<<end1;
 	}
 	cout<<x<<end1;
 }


 /*
 ### Output ###
 1
 3
 5
 */

        Here the value of innermost x is 1, out of this block value is 3 and out of this block is 5.

      • static:storage class

        1. Static variables can be used anywhere in the program inside or outside of a function or block
        2. The value of a static variable exits untill the end of program
        3. The satic variable which is declared inside a function is called "internal static variable" and it can not be used outside that function
        4. The static variable which is declared outside a function is called external variable" and it can be used in all the function of that program


      • Example

         #include<iostream>
 using namespace std;
 void demo()
 {
 	static it x=0;
 	cout<<x<<end1;
 	x++;
 }
 int main()
 {
 	Demo(); 	// calling
 	Demo();
 	Demo();
 	Demo();
 }
 


 /*
 ### Output ###
 0
 1
 2
 3
 */

        Here the Demo function is called four times and each time value is incremented by one.

      • Register:storage class

        1. registr variables is stored in one of the register of system, instead of memory
        2. Value stored in register can be accessed faster than one that is stored in memory


      • Example

         #include<iostream>
 using namespace std;
 int main()
 {
 	register int x,y=20,z=30;
 	x=y+z;
 	cout<<"Add="<<x
 }
 


 /*
 ### Output ###
 Add=50
 */

      • external:storage class

        1. Variable that can be used any where in the program is called external variable
        2. External storage class does not create a variable, but its inform the compiler of its existence
        3. extern keyword is used to declare external variable


      • Example

         #include<iostream>
 using namespace std;
 int x=10; 	// extarnal variable
 int main()
 {
 	extern int x=5;
 	cout<<x;
 }
 


 /*
 ### Output ###
 5
 */
Keyword in C++

  • Definition

    1. The word that has a predefined meaning is called keywords
    2. It's functionality is also predefined
    3. It can not be used as an identifier

  • Keywords in C++ are givien below:

     1. default
 2. float
 3. register
 4. struct
 5. volatile
 6. break
 7. do
 8. for
 9. return
 10. switch
 11. while
 12. case
 13. double
 14. goto
 15. short
 16. typedef
 17. char
 18. else
 19. if
 20. signed
 21. union
 22. const
 23. enum
 24. int
 25. sizeof
 26. unsigned
 27. countinue
 28. extern
 29. long
 30. static
 31. void
 32. auto
Data Types in C++

  • Definition

    1. It is a type of data which is used in the program
    2. There are many predefined data types in C/C++ library like int,char, float etc




  • Integer Type



  • Float Type



  • Character Type



Operator in C++

  • Operator It is a special symbol which is used to perform logical or mathematical operation on data or variable.

  • operand It is a data or variable on which the operation is to be performed.

  • Types of Operator

    • Arithmetic Operators
    • Relational Operators
    • Logical Operators
    • Assignment Operators
    • Bitwise Operators
    • Increment/Decrement Operators
    • Conditional Operators
    • Special Operators

  • Arithmetic Operators



     #include<iostream>
 using namespace std;
 int main()
 {
 	int a=5,b=3;
 	cout<<(a+b)<<"\n";
 	cout<<(a-b)<<"\n";
 	cout<<(a*b)<<"\n";
 	cout<<(a/b)<<"\n";
 	cout<<(a%b)<<"\n"; 	// %(modulus) holds remainder
 }

 /*
 ### Output ###
 8
 2
 15
 1
 2
 */

  • Relational Operators




  • Logical Operators



     #include<iostream>
 using namespace std;
 int main()
 {
 	int a=10,b=50,c=30;
 	if(a>b&&a>c)
 	cout<<"a is greater";
 	if(b>a&&b>c)
 	cout<<"b is greater";
 	if(c>a&&c>b)
 	cout<<"c is greater";
 }

 /*
 ### Output ###
 b is greater
 */

  • Assignment Operators



     #include<iostream>
 using namespace std;
 int main()
 {
 	int x1=5,y1=3;
 	x1+=y1; 	// x1=x1+y1
 	cout<<"x1="<<x1<<"\n";

 	int x2=5,y2=3;
 	x2-=y2; 	// x2=x2-y2
 	cout<<"x2="<<x2<<"\n";

 	int x3=5,y3=3;
 	x3*=y3; 	// x3=x3*y3
 	cout<<"x3="<<x3<<"\n";

 	int x4=5,y4=3;
 	x4/=y4; 	// x4=x4/y4
 	cout<<"x4="<<x4<<"\n";

 	int x5=5,y5=3;
 	x5%=y5; 	// x5=x5%y5
 	cout<<"x5="<<x5<<"\n";
 }

 /*
 ### Output ###
 x1=8
 x2=2
 x3=15
 x4=1
 x5=2
 */

  • Bitwise Operators



     #include<iostream>
 using namespace std;
 int main()
 {
 	int a=5,b=3,c; 	// variable declaration
 	c=a&b; 	 	// AND operation
 	cout<<"a&b="<<c<<"\n";
 	c=a|b; 	 	// OR operation
 	cout<<"a|b="<<c<<"\n";
 	c=a>>2; 	 	// shift right operation
 	cout<<"a>>2="<<c<<"\n";
 	c=a<<2; 	 	// shift left operation
 	cout<<"a<<2="<<c<<"\n";
 	
 }

 /*
 ### Output ###
 a&b=1
 a|b=7
 a>>2=1
 a<<2=20
 */

  • Increment/Decrement Operators



     #include<iostream>
 using namespace std;
 int main()
 {
 	int a=5,b=10;
 	cout<<++a<<end1;
 	cout<<--b;
 }

 /*
 ### Output ###
 6
 9
 */

  • Conditional Operators



     #include<iostream>
 using namespace std;
 int main()
 {
 	int a=10,b=20;
 	a>b?
 	cout<<"a is greater than b":cout<<"b is greater than a";
 }

 /*
 ### Output ###
 b is greater than a
 */

  • Special Operators



IF Statement in C++
  • IF Statement

    • Syntax



      1. If the condition is true its body execute otherwise does not execute
      2. In the case of if in the place of condition always zero and non-zero value is checked.
      3. In which zero means condition false and non-zero means condition true.

      • Example

         #include<iostream>
 #include<conio.h>
 int main()
 {
 	// Assign value to the variable 
 	int x=50,y=20;
 	// checking the condition
 	if(x>y)
 	{
 		cout<<"x is greater than y";
 	}
 }


 /*
 ### Output ###
 x is greater than y
 */

      Click for Practical Program

  • IF else statement

    • Syntax

      1. If the condition is true, 'if' part is executes and if the conditions is false, 'else' part is execute
      2. In the case of 'if' in the condition always zero and non-zero value is checked
      3. In which zero means condition false and non-zero means condition true

    • Example

        #include<iostream>
  int main()
  {
  	// Assign value to the variable 
  	int x=50,y=20;
  	// checking the condition
  	if(x==y)
  	{
  		cout<<"x is equal to y";
  	}
  	else
  	{
  		cout<<"x is not equal to y";
  	}
  }


  /*
  ### Output ###
  // In the above program condition is 'false' because te value of x=50 and y=20 and they are not equal, so 'else' part will execute

  x is not equal to y
  */

    Click for Practical Program

  • IF else ladder statement

    • Syntax

      1. It is a part of conditional statement that executes only one condition at a time
      2. If all condition are false then 'else' part executes
      3. It executes that condition that becomes first true from the top
      4. In the case of 'if' in the place of condition always zero and non-zero value is checked in which zero means condition 'false' and non-zero means conditon 'true'

    • Example

        #include<iostream>
  int main()
  {
  	// Assign value to the variable 
  	int x=10;
  	if(x>5) 	// checking the condition
  	{
  		cout<<"x is greater than 5";
  	}
  	else if(x<8) 	// checking the condition
  	{
  		cout<<"x is less than 8";
  	}
  	else if(x==10) 	// checking the condition
  	{
  		cout<<"x is equal to 10";
  	}
  	else
  	{
  		cout<<"No one condition is true";
  	}
  }


  /*
  ### Output ###
  x is greater than 5
  */

      Note: As we can see from the above program, there are three conditions in which first and third condition are true but the it executes only one condition that becomes first true from the above so the output is "x is greater than 5"

    Click for Practical Program

  • Nested IF

    • Syntax

      1. Nested means "one inside another", so one 'if' inside another 'if' is called 'nested if'
      2. In case of 'if' in the place of condition always zero and non-zero value is checked in which zero means condition 'false' and non-zero means condition 'true'

    • Example

        #include<iostream>
  int main()
  {
  	// Assign value to the variable 
  	int x=10;
  	if(x>5) 	// checking the condition
  	{
  		if(x<15) 	// checking the condition
  		{
  			cout<<"x is greater than 5 and less than 15";
  		}
  	}
  	
  }


  /*
  ### Output ###
  x is greater than 5 and less than 15
  */

      Note: In the above program the outer 'if' condition is 'true', so it's body will execute and the condition of inner 'if' is also 'true', so the output is "x is greater than 5 and less than 15"

      Click for Practical Program

Switch in C++

  • Definition

    Switch statement allows us to execute one statement from many statement and that statements are called case.

    Actually in switch statement, inside the body of switch a number of cases are used and a parameter are passed and from which cas this parameter is matched, executed.



    • Syntax

      1. IN the switch statement a value/number is passed in the place of parameter and that case will execute which is equal to the value/number.
      2. If no case matched with parameter then default case will execute.

    • Example

            #include<iostream>
  	int main()
  	{
  		// Assigning parameter;s value 
  		int p=2;
  		switch(p)
  		{
  			case 1:
  			cout<<"it is case 1";
  			break;
  			case 2:
  			cout<<"it is case 2";
  			break;
  			case 3:
  			cout<<"it is case 3";
  			break;
  			default:
  			cout<<""no case matched";
  		}
  		return 0;
  		
  	}


  	/*
  	### Output ###
  	it is case 2 	// because p=2 so case 2 will execute
  	*/

      Click for Practical Program

Loop-Type in C++
  • For Loop

    • Definition

      To run the body countinously untill a required condition is fullfill is called looping.

      When the condition will become 'false' the execution of loop will be stopped.

    • Syntax



      1. In 'for loop' there are three part: initialization, condition and increment/decrement
      2. Initialization part executes only once
      3. All the three part of 'for loop' are optional

      • Example

         #include<iostream>
 int main()
 {
 	for(int i=1;i<=10;i++)
 	{
 		cout<<i<<"\n";
 	}
 }


 /*
 ### Output ###
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10

 */

        In the above program, 'i' is a variable which is initialized with 1, condition goes to 10 and it is incremented by 1.

        So the output will be 1 to 10.


      Click for Practical Program

  • While Loop
    • Definition
      • To run the body countinously untill a required condition is fullfill is called "looping".
      • It is used to perform looping operation, when the condition will become false the execution of loop will be stopped


    • Syntax

      1. Its body will execute until the given condition is true

    • Example

        #include<iostream>
  int main()
  {
  	
  	int i=1;
  	while(i<=10)
  	{
  		cout<<i<<"\n";
  		i++;
  	}
  }


  /*
  ### Output ###
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10

  */

      In the above program, 'i' is a variable which is initialized with '1', condition goes to 10 and it is incremented by 1 so the output will be 1 to 10.

    Click for Practical Program

  • Do While Loop - **Definition** - To run the body countinously untill a required condition is fullfill is called "looping". - It is used to perform looping operation, when the condition will become false the execution of loop will be stopped

    • Syntax

      1. Its body will execute until the given condition is true.

    • Example

        #include<iostream.h>
  int main()
  {
  	int i=1;
  	do
  	{
  		cout<<i<<"\n";
  		i++;
  	}
  	while(i<=10);
  }


  /*
  ### Output ###
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10

  */

      Note: In the above program, 'i' is a variable which is initialixed with '1', conditin goes to 10 and it is incremented by 1 so the output will be 1 to 10.

    Click for Practical Program

  • Nested Loop

    • Definition A loop inside another loop is called "nested loop", so one 'for loop' inside another 'for loop' is called "nested loop"

    • Syntax



    • Example

        #include<iostream.h>
  int main()
  {
  	int n;
  	cout<<"Enter number upto you want to print prime number\n";
  	cin>>n;
  	for(int i=2;i<=n;i++)
  	{
  		int no=i,m=0;
  		for(int j=2;j<=no-1;j++)
  		{
  			if(no%j==0)
  			m=1;
  		}
  		if(m==0)
  		cout<<no<<" ";
  	}
  	
  }


  /*
  ### Output ###
  Enter number upto you want to print prime number
  20
  2 3 5 7 11 13 17 19 
  */

      Click for Practical Program

Pointer in C++

  • Definition

    1. It is a special type of variable which is used to store the address of another variable
    2. It can store the address of same data types (i.e an integer pointer can store the address of integer variable, character pointer can store the address of character variable and so on)
    3. If we add asterik(*) symbol with anny variable at the time of dclaring variable, then this variable is called "pointer variable"
    4. We use ampersand symbol to get the address of variable
      • symbol is used to get the value at address which is hold by pointer


  • Syntax

    1. Here 'a' is a normal variable
    2. 'p' is apointer variable because it is associated with * symbol

  • Example

    
#include<iostream.h>
int main()
{
	int a=10; 	// initializing normal variable
	int *p; 	// declaring pointer variable
	p=&a; 	// address of variable a is assigned to p
	cout<<"value of a="<<a;
	cout<<"address of a="<<&a;
	cout<<"value of p="<<p;
	cout<<"address of p="<<&p;
	cout<<"value of *p="<<*P; 
}


/*
### Output ###
value of a=10
address of a=8284
value of p=8284
address of p=8288
value of *p=10

*/

  • Output Explanation Assume that the addres of variable a is 8284 and address of variable p is 8288, it may be different in your system



Click for Practical Program

Arrays in C++
  • Single Dimension Array

    • Definition

      1. It is a collection of data of same data type
      2. It is used to store group of data simultaneously
      3. It can store data of the same data type (i.e an integer array can store only integer value, character array can store only character value and so on)
      4. We can not fetch data from array directly , therefore, we use index point
      5. The indexing of array alway start with '0'
      6. Index value is always an integer number
      7. Array may be of any data type like int,char,float etc

    • Syntax



      1. Here 'a' is the name of array
      2. 'int' is the data type of array
      3. Size of array is 5 means, we can store maximum of 5 values in this array

    • Initialization of array (method 1)



    • Initialization of array (method 2)



    • Printing of array element (method 1)

      
#include<iostream>
using namespace std;
int main()
{
	int a[5]={20,10,80,70,60};
	cout<<"value at a[0]="<<a[0]<<"\n";
	cout<<"value at a[1]="<<a[1]<<"\n";
	cout<<"value at a[2]="<<a[2]<<"\n";
	cout<<"value at a[3]="<<a[3]<<"\n";
	cout<<"value at a[4]="<<a[4]<<"\n";
}


/*
### Output ###
value at a[0]=20
value at a[1]=10
value at a[2]=80
value at a[3]=70
value at a[4]=60

*/

    • Printing of array element using loop (method 2)

      
#include<iostream>
using namespace std;
int main()
{
	int a[5]={20,10,80,70,60};
	for(int i=0;i<=4;i++)
	cout<<"value at a["<<i<<"]="<<a[i]<<"\n";
}


/*
### Output ###
value at a[0]=20
value at a[1]=10
value at a[2]=80
value at a[3]=70
value at a[4]=60

*/

    • User input in array

      
#include<iostream>
using namespace std;
int main()
{
	int a[5];
	cout<<"Enter element 1=";
	cin>>a[0];
	cout<<"Enter element 2=";
	cin>>a[1];
	cout<<"Enter element 3=";
	cin>>a[2];
	for(int i=0;i<=2;i++)
	cout<<"Value at a["<<i<<"]="<<a[i]<<"\n";
	
}


/*
### Output ###
Enter element 1=45
Enter element 2=20
Enter element 3=60
value at a[0]=45
value at a[1]=20
value at a[2]=60

*/

    • User input in array using loop

      
#include<iostream>
using namespace std;
int main()
{
	int a[5],i;
	for(int i=0;i<=2;i++)
	{
		cout<<"Enter element "<<i+1<<"=";
		cin>>a[i];
	}
	for(int i=0;i<=2;i++)
	cout<<"Value at a["<<i<<"]="<<a[i]<<"\n";
	
}


/*
### Output ###
Enter element 1=45
Enter element 2=20
Enter element 3=60
value at a[0]=45
value at a[1]=20
value at a[2]=60

*/

      Click for Practical Program

  • Double Dimension Array

    • Definition

      1. It is a collection of data of same data type
      2. It is used to store group of data simultaneously
      3. It can store data of the same data type (i.e an integer array can store only integer value, character array can store only character value and so on)
      4. We can not fetch data from array directly , therefore, we use index point
      5. The indexing of array alway start with '0'
      6. Index value is always an integer number
      7. Array may be of any data type like int,char,float etc

    • Syntax



      1. Here 'a' is the name of array
      2. 'int' is the data type of array
      3. Size of array is 3x3 means, we can store maximum of 9 values in this array

    • Initialization of array (method 1)



    • Initialization of array (method 2)



    • Printing of array element (method 1)

      
#include<iostream>
using namespace std;
int main()
{
	int a[3][3]={{10,20,30},{70,80,90},{40,50,60}};
	cout<<"value at a[0][0]="<<a[0][0]<<"\n";
	cout<<"value at a[0][1]="<<a[0][1]<<"\n";
	cout<<"value at a[0][2]="<<a[0][2]<<"\n";
	cout<<"value at a[1][0]="<<a[1][0]<<"\n";
	cout<<"value at a[1][1]="<<a[1][1]<<"\n";
	cout<<"value at a[1][2]="<<a[1][2]<<"\n";
	cout<<"value at a[2][0]="<<a[2][0]<<"\n";
	cout<<"value at a[2][1]="<<a[2][1]<<"\n";
	cout<<"value at a[2][2]="<<a[2][2]<<"\n";
	
}


/*
### Output ###
value at a[0][0]=10
value at a[0][1]=20
value at a[0][2]=30
value at a[1][0]=70
value at a[1][1]=80
value at a[1][2]=90
value at a[2][0]=40
value at a[2][1]=50
value at a[2][2]=60

*/

    • Printing of array element using loop (method 2)

      
#include<iostream>
using namespace std;
int main()
{
	int a[3][3]={{10,20,30},{70,80,90},{40,50,60}};
	for(int i=0;i<=2;i++)
	{
		for(int j=0;j<=2;j++)
		{
			cout<<[i][j]<<" ";
		}
		cout<<"\n";
	}
}


/*
### Output ###
10 20 30
70 80 90
40 50 60

*/

    • User input in array using loop

      
#include<iostream>
using namespace std;
int main()
{
	int a[3][3];
	int i,j;
	cout<<"Enter 9 element one by one\n";
	for(int i=0;i<=2;i++)
	  for(int j=0;j<=2;j++)
	   cin>>a[i][j];
	cout<<"Element is given below\n";
	for(int i=0;i<=2;i++)
	{
		for(int j=0;j<=2;j++)
		{
			cout<<a[i][j]<<" ";
		}
		cout<<'\n";
	}
}


/*
### Output ###
Enter 9 element one by one
5
6
5
8
7
9
3
1
5
Element is given below
5 6 5
8 7 9
3 1 5

*/

      Click for Practical Program

Functions in C++
  • Function

    • Definition

      1. It is a collection of statement that performs a specific task
      2. It execute when it is called by its name
      3. A large program is devided into a number of small building block for simplicity and this building block is called function
      4. We can call a function again and again
      5. The most important features of function is code reusability
      6. The C library provides many pre-defined functions

    • Syntax



    • Key point about the function

      • Function Declaration: At this stage the function is declared.

      For example: void add()

      • Function Definition: This is the place where actual code is written to perform the task.

      For example

      
 	void add()
 	{
 		int x,y=20,z=30;
 		x=y+z;
 		cout<<"Add="<<x;
 	};

      • Function Calling: At this stage the function is called.

        For example: add();

    • Complete Example

      
 	#include <iostream>
 	using namespace std;
 	void add(); 	// function declarartion
 	void add() 	// function definition
 	{
 		int x,y=20,z=30;
 		x=y+z;
 		cout<<"Add="<<x;
 	}
 	int main()
 	{
 		add(); 	// function calling
 	}

    • Types of Function

      There are two types of function

      • Predefined Function

      The function which is predefined in the library is called predefined function. Example:- printf(), scanf(), clrscr(), getch() etc

      • Userdefined Function

      The function is made by the user is called userdefined function. Example:- add(), sub(), multi(). div() [Note: These are userdefined name, it may different]

    • Category of Userdefined Function

      There are four category of userdefined function:

      • Function with no return type and no parameter
      • Function with no return type and with parameter
      • Function with return type and no parameter
      • Function with return type and parameter

    • Function with no return type and no parameter

      The function in which there is no value returning by that function is called Function with no return type and no parameter

      
 #include<iostream>
 using namespace std;
 void add() 	// function definition
 {
 	int x,y=20, z=30;
 	x=y+z;
 	cout<<"Add="<<x;
 }
 int main()
 {
 	add(); 	// function calling
 }


 /*
 ### Output ###
 Add=50
 */

      In the above example there is no parameter and no return type

    • Function with no return type and with parameter

      The function in which there is some parameter and there is no value returning by that function is called Function with no return type and with parameter

      
 #include<iostream>
 using namespace std;
 void add(int y,int z) 	// function definition
 {
 	int x;
 	x=y+z;
 	cout<<"Add="<<x;
 }
 int main()
 {
 	add(10,20); 	// function calling
 }


 /*
 ### Output ###
 Add=30
 */

      In the above example, there are two parameter of "integer" type namely 'y' and 'z' .

      There at the time of calling two integer value will be passed in which first will assign to y and second will assign to z.

    • Function with return type and with no parameter

      The function in which there is no parameter and there is some value returning by that function is called Function with return type and with no parameter

      
 #include<iostream>
 using namespace std;
 void add() 	// function definition
 {
 	int x,y=20,z=30;
 	x=y+z;
 	return x;
 }
 int main()
 {
 	int rs=add(); 	// function calling
 	cout<<"Add="<<rs; 
 }


 /*
 ### Output ###
 Add=50
 */

      In the above example, there is no parameter but the function will return integer value because there is int keyword in the place of return type and return value will assign to variable rs.

    • Function with return type and with parameter

      The function in which there is some parameter and there is some value returning by that function is called Function with return type and with parameter

      
 #include<iostream>
 using namespace std;
 void add(int y,int z) 	// function definition
 {
 	int x;
 	x=y+z;
 	return x;
 }
 int main()
 {
 	int rs=add(50,30) 	// function calling
 	cout<<"Add="<<rs;
 }


 /*
 ### Output ###
 Add=80
 */

      In the above example, there is no parameter but the function will return integer value because there is int keyword in the place of return type and returned value will assign to variables rs

    • Calling of Function

      There are two ways of calling function:

      • Call By Value
      • Call By Reference

    • Call By Value

      In this type of calling a function direct value is passed at the time of calling.

      
 #include<iostream>
 using namespace std;
 void add(int y,int z) 	// function definition
 {
 	int x;
 	x=y+z;
 	cout<<"Add="<<x;
 }
 int main()
 {
 	add(10,20); 	// function calling
 }


 /*
 ### Output ###
 Add=30
 */

      In the above example we can see that direct value is passed at the time of calling.

    • Call By Reference

      1. In ths type of calling a function, the reference of the value is passed at the time of calling
      2. Reference is also called address
      3. When the address of data is passed at the time of calling so it is neccessary to use pointer in the place of parameter.
      4. For better understanding, see the example below:-
      
 #include<iostream>
 using namespace std;
 void sum(int *p,int *q) 	// function definition
 {
 	int result=*p + *q;
 	cout<<"Sum="<<result;
 }
 int main()
 {
 	int x=10, y=20;
 	// reference of variable is get using ampersand(&) operator
 	sum(&x,&y); 	// function calling with refrence/address
 }


 /*
 ### Output ###
 Add=30
 */

      In the above example, we can see that x and y are normal variable and reference of that variables are passed at the time of calling.

    • Function with default value

      • In this type of function, the functions contains a number of parameter with some initial value [for example: void sum(int x=10,int y=20)]

      • At the etime of calling if there is no value is passed [for example: sum();] then the default value will be x=10 and y=20, but if value passed [for example: sum(5,6);] then the value will be x=5 and y=6

      • For better understanding see the example below:

      
 #include<iostream>
 using namespace std;
 void sum(int x=10,int y=20) 	// function definition
 {
 	int result=x + y;
 	cout<<"Add="<<result<<"\n";
 }
 int main()
 {
 	int x=10, y=20;
 	cout<<"Without value\n";
 	sum(); 	// function calling without value
 	cout<<"With value\n";
 	sum(5,6); 	// function calling with value
 	
 }


 /*
 ### Output ###
 Without value
 Add=30
 With value
 Add=11
 */

    • Passing Array to Function

      In this type of function, there is an array in the place of parameter [for example: void sum(int ar[5])] and its value is passed at the time of calling.

      
 #include<iostream>
 using namespace std;
 void sum(int ar[5]) 	// function definition
 {
 	int s=0;
 	for(int i=0;i<5;i++)
 	s=s+ar[i];
 	cout<<"Total suum of element="<<s;
 }
 int main()
 {
 	int x[5]={10,20,50,40,60};
 	sum(x); 	// function calling with array
 	
 }


 /*
 ### Output ###
 Total sum of element=180
 */

      In the above example, we can see that there is an array ar[5] in place of parameter and there as another array x[5]={10,20,50,40,60} and it is passed at the etime of calling therefore the value of array x will be copied into array ar.

    • Recursion

      The process of calling a function by itself is called Recursion and the function that calls itself is called Recursive Function.

      Factorial of any Number using recursion
      Factorial of 5=5      4321

      
 #include<iostream>
 using namespace std;
 void factorial(int no,int f) 	// function definition
 {
 	if(no>=1)
 	{
 		f=f*no;
 		no--;
 		factorial(no,f);
 	}
 	else
 	cout<<"Factorial ="<<f;
 }
 int main()
 {
 	int n;
 	cout<<"Enter any number to find factorial\n";
 	cin>>n;
 	factorial(n,1); 	// function calling with array
 	
 }


 /*
 ### Output ###
 Enter any number to find factorial
 6
 Factorial =720
 */

      Click for Practical Program

  • String Function

    • Definition

      1. Sring is a collection of character
      2. C does not support string data type. Therefore char data type is used to make string
      3. String in C is stored in single dimension character array
      4. There are many predefined string function in C library
      5. All the string functions are predefined in string.h header file


    • strlen(s)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char name[200]="Easy";
 	cout<<strlen(name);
 	return 0;
 }


 /*
 ### Output ###
 4 	// because there is 4 character in Easy
 */



    • strcpy(s1,s2)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char name1[200]="Prosper";
 	char name2[200]="Nemo";
 	strcpy(name1,name2);
 	cout<<name1;
 	return 0;
 }


 /*
 ### Output ###
 Nemo
 */



    • strcmp(s1,s2)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char s1[200]="Easy";
 	char s2[200]="Easy";
 	if(strcmp(s1,s2)==0);
 	{
 		cout<<"string s1 and string s2 are same.";
 	}
 	else
 	{
 		cout<<"string s1 and string s2 are not same.";
 	}
 	return 0;
 }


 /*
 ### Output ###
 string s1 and string s2 are same.
 */



    • strcat(s1,s2)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char s1[200]="Easy";
 	char s2[200]="Programming";
 	cout<<,strcat(s1,s2);
 	return 0;
 	
 }


 /*
 ### Output ###
 Easy Programming
 */



    • strrev(s)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char s1[200]="ABCD";
 	cout<<,strrev(s);
 	return 0;
 	
 }


 /*
 ### Output ###
 DCBA
 */



    • strupr(s)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char s[200]="Easy";
 	cout<<,strupr(s);
 	return 0;
 	
 }


 /*
 ### Output ###
 EASY
 */



    • strlwr(s)

      
 #include<iostream.h>
 #include<conio.h>
 #include<string.h>
 int main()
 {
 	char s[200]="Easy";
 	cout<<,strlwr(s);
 	return 0;
 	
 }


 /*
 ### Output ###
 easy
 */



      Click for Practical Program

  • Math Function

    • Definition

      1. It is used to perform the mathematical related operation
      2. There are many predefined math function in C libray
      3. All the math function are predefined in math.h header file



    • Example:

      
 #include<iostream.h>
 #include<conio.h>
 #include<math.h>
 int main()
 {
 	float a=2;
 	cout<<"sin(2)="<<sin(a)<<"\n";
 	cout<<"sin(2)="<<cos(a)<<"\n";
 	cout<<"sin(2)="<<tan(a)<<"\n";
 	cout<<"sin(2)="<<exp(a)<<"\n"; 	// exponential
 	cout<<"sin(2)="<<log(a)<<"\n";	 // natural log
 	cout<<"sin(2)="<<log10(a)<<"\n"; 	// log10
 	cout<<"sin(2)="<<sqrt(a)<<"\n"; 	// square root
 	cout<<"sin(2)="<<cbrt(a)<<"\n"; 	// cube root
 	return 0;
 }


 /*
 ### Output ###
 sin(2)=0.909
 cos(2)=-0.416
 tan(2)=-2.185
 exp(2)=7.389
 log(2)=0.693
 log10(2)=0.301
 sqrt(4)=2
 cbrt(27)=3
 */

    • floor() function:- It always return minimum round off value

      
 #include<iostream.h>
 #include<conio.h>
 #include<math.h>
 int main()
 {
 	cout<<"sin(2)="<<floor(2.3)<<"\n";
 	cout<<"sin(2)="<<floor(2.5)<<"\n";
 	cout<<"sin(2)="<<floor(2.8)<<"\n";
 	return 0;
 }


 /*
 ### Output ###
 2.0
 2.0
 2.0
 */

    • ceil() function:- It always return maximum round of value

      
 #include<iostream.h>
 #include<conio.h>
 #include<math.h>
 int main()
 {
 	cout<<"sin(2)="<<ceil(2.3)<<"\n";
 	cout<<"sin(2)="<<ceil(2.5)<<"\n";
 	cout<<"sin(2)="<<ceil(2.8)<<"\n";
 	return 0;
 }


 /*
 ### Output ###
 3.0
 3.0
 3.0
 */

    • round() function

      
 #include<iostream.h>
 #include<conio.h>
 #include<math.h>
 int main()
 {
 	cout<<"sin(2)="<<round(2.3)<<"\n";
 	cout<<"sin(2)="<<round(2.5)<<"\n";
 	cout<<"sin(2)="<<round(2.8)<<"\n";
 	return 0;
 }


 /*
 ### Output ###
 2.0
 3.0
 3.0
 */
Structure in C++
  • Structure

    • Definition

      1. It is a collection of data of different data type
      2. It is a user define data type
      3. Data can be of int, char, float, double etc data type
      4. We can access the member of structure by making the variable of structure
      5. struct keyword is used to create a structure

    • Syntax



    • Example:

      
 	struct student
 	{
 		char name[200];
 		int rollno;
 		float marks;
 	};

      Here:

      1. student is the name of structure
      2. struct is a keyword

    • Example:- Write a program to store and display the student name, rollno and marks

      
 	#include <iostream.h>
 	#include <string.h>
 	struct student
 	{
 		char name[200];
 		int rollno;
 		float marks;
 	};
 	int main()
 	{
 		struct student student1; 	// declaring structure variable
 		strcpy(student1.name,"Nemo");
 		student1.rollno=201;
 		student1.marks=85.9;
 			cout<<"Student Name="<<student1.name<<"\n";
 			cout<<"Student Rollno="<<student1.rollno<<"\n";
 			cout<<"Student Marks="<<student1.marks<<"\n";
 	}
 

 	### output ###
 	Student Name=Nemo
 	Student Rollno=201
 	Student Marks=85.9

    Click for Practical Program

  • Union

    • Definition

      1. It is a collection of data of different data type
      2. It is a user define data type
      3. Data can be of int, char, float, double etc data type
      4. We can access the member of union by making the variable of union
      5. union keyword is used to create a union
      6. Note: Union does not support multiple value simultaneously.
        It can only store one value at a time.

    • Syntax



    • Example:

      
 	union student
 	{
 		char name[200];
 		int rollno;
 		float marks;
 	};

      Here:

      1. student is the name of union
      2. union is a keyword

    • Example:- Write a program to store and display the student name, rollno and marks

      Note:

      • Union will show only one last value correct cause it can store only single value at a time
      • I am writing this program here so you can understsand difference b/w structure and union better
      
 	#include <iostream.h>
 	#include <string.h>
 	union student
 	{
 		char name[200];
 		int rollno;
 		float marks;
 	};
 	int main()
 	{
 		union student student1; 	// declaring structure variable
 		strcpy(student1.name,"Nemo");
 		student1.rollno=201;
 		student1.marks=85.9;
 			cout<<"Student Name="<<student1.name<<"\n";
 			cout<<"Student Rollno="<<student1.rollno<<"\n";
 			cout<<"Student Marks="<<student1.marks<<"\n";
 	}
 

 	### output ###
 	Student Name=garbage value
 	Student Rollno=garbage value
 	Student Marks=85.9

    Click for Practical Program

  • Enumeration

    • Definition

      1. It is a collection of named integer constant
      2. It is a user define data type
      3. enum keyword is used to create a enumeration
      4. Note: Union does not support multiple value simultaneously.
        It can only store one value at a time.

    • Syntax



    • Example:

      
 	enum week {sunday,monday,tuesday,wednesday,thursday,friday,saturday};

      Here:

      1. enum is a keyword
      2. week is the name of union and its a user defined data type
      3. sunday,monday,tuesday,wednesday,thursday,friday,saturday are the values of enum

    • Default numerical value of the member of enum is given below:

      • Default value of sunday is 0
      • Default value of monday is 1
      • Default value of tuesday is 2
      • Default value of wednesday is 3
      • Default value of thursday is 4
      • Default value of friday is 5
      • Default value of saturday is 6

      for better understanding, see the below example:

    • Example 1:-

      
 	#include <iostream.h>
 	using namespace std;
 	enum week {sunday,monday,tuesday,wednesday,thursday,friday,saturday};
 	int main()
 	{
 		enum week obj;
 		obj=wednesday;
 		cout<<"Value of wenesday"<<obj;
 	}
 	

 	### output ###
 	Value of wenesday=3

    • Example:- We can aslo change the default value of member of enum

      
 	#include <iostream.h>
 	using namespace std;
 	enum week {sunday=20,monday=50,tuesday=18,wednesday=95,thursday=84,friday=60,saturday=55};
 	int main()
 	{
 		enum week obj;
 		obj=wednesday;
 		cout<<"Value of wenesday"<<obj;
 	}
 	

 	### output ###
 	Value of wenesday=95

    Click for Practical Program

File Handling in C++

  • Definition

    1. File handling is mechanism to store the output of a program into a file and read from the file on the disk permanently

    2. fstream header file is used to perform file operator in C++, this header file provides many classes (ifstream, ofstream, fstream) to read from a file and write into a file

    3. ofstream: This data type represenets the output file stream and is used to create files and to write information to files

    4. ifstream: This data type represents the input file stream and is used to read information from files

    5. fstream: This data type represents the file stream generally, and has the capabilities of both ofstream and ifstream which means it can create files, write information to files, and read information from files.

  • Operation on File

    1. Opening of file
    2. Writing into a file
    3. Appending data into a file
    4. Reading from a file
    5. Closing of file

  • File Opening Modes

    • In C++ File can be open in different mode to perform read and write operation on a file.

    • open() function is used to open a file

    • open functions takes two arguments open(const char *filename, ios::openmode mode);

    • Different file opening mode is given below:




  • Writing into a file

     #include <iostream>
 #include <fstream>
 using namespace std;
 int main() {
 	ofstream ofile; 	// making object of class ofstream
 	ofile.open("easy.txt"); 	// open "easy.txt" for writing data

 	// write to a file
 	ofile << "Nemonet TYP" << end1;
 	ofile << "An ISO 9001:2023 Certified Programmer" << end1;
 	ofile.close(); 	// close the file
 	return 0;
 }

  • Reading from a file

     #include <iostream>
 #include <fstream>
 using namespace std;
 int main() 
 {
 	char str[100]; 	// Declaring variables to store data from file
 	ifstream ifile; 	// making object of class ifstream
 	ifile.open("easy.txt"); 	// open "easy.txt" for reading
 	cout << "Content of easy.txt file is given below :-"<<end1;

 	// while the end of file [ eof() ] is not reached
 	while (!ifile.eof()) {
 		ifile.getline(str, 100); 	// read a line from file
 		cout << str << end1; 	// print the file content
 	}
 	ifile.cose(); 	// close the file
 }

  • Example: Count number of alphabet in a file

     #include <iostream>
 #include <fstream>
 using namespace std;
 int main() 
 {
 	ifstream fin("easy.txt");
 		char ch;
 		int i,alpha=0;
 		while(fin)
 		{
 			fin.get(ch);
 			i=ch;
 			if((i >=65 && i <=90) || (i >=97 && i <=122))
 			alpha++;
 		}
 		cout<<"\n No. of alphabelt in easy.txt file : "<<alpha;
 }

 /* 
 easy.txt must exist in your system
 */

  • Example: Count number of digits in a file

     #include <iostream>
 #include <fstream>
 using namespace std;
 int main() 
 {
 	ifstream fin("easy.txt");
 		char ch;
 		int i,digit=0;
 		while(fin)
 		{
 			fin.get(ch);
 			i=ch;
 			if(i >=48 && i <=57)
 			dgit++;
 		}
 		cout<<"\n No. of digits in easy.txt file : "<<digit;
 }

 /* 
 easy.txt must exist in your system
 */

  • Example: Count number of special symbol in a file

     #include <iostream>
 #include <fstream>
 using namespace std;
 int main() 
 {
 	ifstream fin("easy.txt");
 		char ch;
 		int i,ss=0;
 		while(fin)
 		{
 			fin.get(ch);
 			i=ch;
 			if((i >=65 && i <=90) || (i >=97 && i <=122))
 			{}
 			else if(i >=48 && i <=57)
 			{}
 			else
 			ss++;
 		}
 		cout<<"\n No. of special symbol in easy.txt file : "<<ss;
 }

 /* 
 easy.txt must exist in your system
 */

  • Example: Count number of space in a file

     #include <iostream>
 #include <fstream>
 using namespace std;
 int main() 
 {
 	ifstream fin("easy.txt");
 		char ch;
 		int i,space=0;
 		while(fin)
 		{
 			fin.get(ch);
 			i=ch;
 			if(ch=='')
 			space++;
 		}
 		cout<<"\n No. of space in easy.txt file : "<<space;
 }

 /* 
 easy.txt must exist in your system
 */




Note:

  • This Tutorial is mainly Practical.
  • Give a STAR if you like this
  • FORK to get more update
  • Make a PULL REQUEST to countribute