Go Programming Tutorial

1. Introduction to Go Programming

What is Go?
- Simple but fast, popular programming language for cloud engineering
- statically typed, compiled programming language
- Developed by google in 2007
- Open sourced in 2009
- Often known as golang
- Syntax has similarity with C,C++
- Mainly used as a server side or backend language
- Supports cross-os
Why Go?
- For making simple, reliable and efficient computer program/software
- Helps to create high performance applications but use less resources
- It helps to write concurrent multithread programs
Prerequisities
- Nothing, but knowing C/C++ or any programming language is an advantage

2. Go Program structure

package declaration - every go program is consist of packages. it is a mandatory thing. it has to be the first statement of go program.
import packages
function
statement

  // main.go
  package main

  import “fmt”

  func main() {

    fmt.Println(“My name is Anisul Islam”)

  }

  output: My name is Anisul Islam

3. Environment setup

IDE / Text Editor -> Any text editor- notepad / notepad++ / VSCode (free), Vim (free) / GoLand (paid)
Go compiler -> compiler translate the source code into machine/executable code so that machine can understand the instructions
go extension for VSCode

4. First Go Program

A simple go program

// filename: main.go
// a program for printing student details
package main

import "fmt"

func main() {
  fmt.Println("Anisul Islam is a student")
  fmt.Println("Anisul Islam is 32 years old")
  fmt.Println("Anisul Islam has got GPA 3.92/5 in SSC")
  fmt.Print("Anisul Islam originally from Bangladesh");
}

running the program
- go mod init project-name
- go run fileName.go

5. Tokens - Escape sequences & comments

Token of any programming language
- keywords
- data types
- variables
- Escapse sequences
- operators

escape sequences example

  package main
  import "fmt"
  func main(){
    fmt.Print("Name \t Age\n")
    fmt.Print("----- \t ------\n")
    fmt.Print("Anis \t 32\n")
    fmt.Print("Rakib \t 29\n")
  }

there are 2 types of comment is available in Go -> single line, multiple line comment. comments are ignored by the compiler.
```
  // single line comment
  /*
    multiple
    line
    comment
  */
```

6. Keywords & Data types

keywords: keywords are reserved words.
Data types: boolean, string, numeric - integer, floating, derived types - pointer, array, structure, slice, map, interface etc.

example of data types

  "anisul islam" -> string type
  21 -> int type
  21.5 -> floating type
  true/false -> bool

  // more on int, float
  variation of integer-> int8 (8 bits), int16, int32, int64, uint8 (only positive 0 to 255), uint6, uint32, uint64

  variation of float-> float32, float64

7. Variables

syntax of variable declaration: var variable1, variable2, ... variableN dataType
variable naming convention (camelcasing)

example

  package main
  import "fmt"
  func main(){
    // static variable declaration
    var name, country string
    var age int
    var gpa float32

    // variable initialization
    name = "anisul islam"
    country = "Bangladesh"
    age = 32
    gpa = 3.92

    // dynamic variable declaration + initialization
   //  var name = "Anisul Islam"
   //  var country = "Bangladesh"
   //  var age = 32
   //  var gpa = 3.92

   // var name,country,age,gpa = "anisul islam", "Bangladesh", 32, 3.92

   // shortcuts
   // name := "Anisul Islam"
   // country := "Bangladesh"
   // age := 32
   // gpa := 3.92

    fmt.Println(name)
    fmt.Println(name, " is a student")
    fmt.Println(name,"is", age, "years old")
    fmt.Println(name, "has got" , gpa, "/5 in SSC")
    fmt.Print(name,"originally from ", country);
  }

8. Formatting output

 package main
 import "fmt"
 func main(){
    name := "Anisul Islam"
    country := "Bangladesh"
    age := 32
    gpa := 3.92

    fmt.Printf("%v is a student\n", name)
    fmt.Printf("%v is %v years old\n", name, age)
    fmt.Printf("%v has got GPA %v/5 in SSC\n", name, gpa)
    fmt.Printf("%v originally from %v\n", name, country);
 }

9. Constants && Getting User Input

Constants indicate to fix values

  package main
  import "fmt"
  func main(){
    var name string
   	const COUNTRY = "Bangladesh"
   	var age, num1, num2 int
   	var gpa float32

		fmt.Printf("Enter your name: ")
		fmt.Scanf("%v", &name)

		fmt.Printf("Enter your age: ")
		fmt.Scan(&age)

		fmt.Printf("Enter your SSC gpa: ")
		fmt.Scanln(&gpa)

		fmt.Printf("Enter 2 numbers: ")
		fmt.Scan(&num1, &num2)

    fmt.Printf("%v is a student\n", name)
    fmt.Printf("%v is %v years old\n", name, age)
    fmt.Printf("%v has got GPA %v/5 in SSC\n", name, gpa)
    fmt.Printf("%v originally from %v\n", name, COUNTRY);
    fmt.Printf("num1 = %v, num2 = %v\n", num1, num2);
  }

10. Number conversion calculator & number formatting

    package main

    import "fmt"
    func main(){


      // string formatting
      // var name = "Anisul Islam"
      // fmt.Printf("%s\n",name)
      // fmt.Printf("%q\n",name)

        // floating number formatting
      // var number = 3.1416
      // fmt.Printf("%.2f\n",number)

      var decimalNumber int

      fmt.Printf("decimal number= ")
      fmt.Scanf("%v", &decimalNumber)

      fmt.Printf("Binary Number = %b\n",decimalNumber)
      fmt.Printf("Octal Number = %o\n",decimalNumber)
      fmt.Printf("Hexa Number = %x\n",decimalNumber)

    }

11. Operators

operator - symbol for doing calculation
Types of operators
- Arithmetic Operators -> +, -, *, /, %
- Assignment Operators -> =, +=, -=, *=, /=, %=
- Unary Operators -> ++, --
- Relational Operators
- Logical operators -> &&, ||, !
- Bitwise operators -> &, |, ^
- others -> , (comma), & (returns address), * (pointer)

example of Arithmetic operator

  package main
  import "fmt"
  func main(){
    // arithmetic operator -> +, -, *, /, %
    var num1, num2 int
    fmt.Printf("num1= ");
    fmt.Scan(&num1)
    fmt.Printf("num2= ");
    fmt.Scan(&num2)

    result := num1 + num2
    fmt.Printf("%v+%v=%v\n", num1, num2, result)

    result = num1 - num2
    fmt.Printf("%v-%v=%v\n", num1, num2, result)

    result = num1 * num2
    fmt.Printf("%v*%v=%v\n", num1, num2, result)

    var result2 =  float32(num1) / float32(num2)
    fmt.Printf("%v/%v=%v\n", num1, num2, result2)

    result = num1 % num2
    fmt.Printf("%v%%%v=%v\n", num1, num2, result)
  }

12. Find the area of triangle and circle

    package main

    import "fmt"
    func main(){

      var radius, area float32

      fmt.Printf("Enter Radius : ")
      fmt.Scan(&radius)

      area = 3.1416 * radius * radius
      fmt.Printf("Area of circle: %v\n",area)

      // a program to calculate area of triangle
      // var base, height, area float32

      // fmt.Printf("Base = ")
      // fmt.Scan(&base)

      // fmt.Printf("Height = ")
      // fmt.Scan(&height)

      // area = 0.5 * base * height

      // fmt.Printf("Area of triangle = %v\n", area)
    }

13. Assignment Operator

    package main

    import "fmt"
    func main(){

        // 2. Assignment Operators -> =, +=, -=, *=, /=, %=

        x := 4

        x = x + 1
        x+=1 // x = x + 1
        x-=1 // x = x - 1
        x*=1 // x = x * 1
        x/=1 // x = x / 1
        x%=1 // x = x % 1

        fmt.Printf("x = %v\n",x)
      }

14. Unary Operator

15. Relational Operator

16. Logical Operator

17. Bitwise Operator

    package main

    import "fmt"
    func main(){

      x := 18      // 18 = 10010
      y := 17      // 17 = 10001
      and := x & y   //16  = 10000
      or := x | y   //19  = 10011
      exor := x ^ y   //3  = 00011
      fmt.Printf("x & y = %v\n",and)
      fmt.Printf("x | y = %v\n",or)
      fmt.Printf("x ^ y = %v\n",exor)

    }

18. if, else if, else control statement

      // with if only
      package main

      import "fmt"
      func main(){
        // a program to determine positive / negative / zero
        number := 10
        if number > 0 {
          fmt.Printf("Positive\n")
        }
        if number < 0 {
          fmt.Printf("Negative\n")
        }
        if number == 0 {
          fmt.Printf("Zero\n")
        }
      }

      // with if, else if
      package main

      import "fmt"
      func main(){
        // a program to determine positive / negative / zero
        number := 10
        if number > 0 {
          fmt.Printf("Positive\n")
        }	else if number < 0 {
          fmt.Printf("Negative\n")
        } else if number == 0 {
          fmt.Printf("Zero\n")
        }
      }

      // with if, else if, else
      package main

      import "fmt"
      func main(){
        // a program to determine positive / negative / zero
        number := 10
        if number > 0 {
          fmt.Printf("Positive\n")
        }	else if number < 0 {
          fmt.Printf("Negative\n")
        } else {
          fmt.Printf("Zero\n")
        }
      }

19. A Go program to determine whether a number is even/odd

    // a go program to determine even/odd
  package main

  import "fmt"
  func main(){
    var number int
    fmt.Printf("Enter any integer: ")
    fmt.Scanf("%v",&number)

    if number % 2 == 0 {
      fmt.Printf("Even\n")
    }	else {
      fmt.Printf("Odd\n")
    }
  }

20. A Go program to find largest number among 3 numbers using relational operators

package main

import "fmt"
func main(){
	var number1, number2, number3 int
	fmt.Printf("Enter 3 numbers: ")
	fmt.Scanf("%v %v %v",&number1, &number2, &number3)

	if number1 > number2 {
		if number1 > number3 {
			fmt.Printf("%v is the largest number\n", number1)
		}else{
			fmt.Printf("%v is the largest number\n", number3)
		}
	}	else if number2 > number1 {
		if number2 > number3 {
			fmt.Printf("%v is the largest number\n", number2)
		}else{
			fmt.Printf("%v is the largest number\n", number3)
		}
	}	else {
		fmt.Printf("Numbers are equal\n")
	}
}

21. A Go program to find largest number among 3 numbers using Logical operators

package main

import "fmt"
func main(){
	var number1, number2, number3 int
	fmt.Printf("Enter 3 numbers: ")
	fmt.Scanf("%v %v %v",&number1, &number2, &number3)

	if (number1 > number2) && (number1 > number3){
			fmt.Printf("%v is the largest number\n", number1)
	}	else if (number2 > number1) && (number2 > number3){
			fmt.Printf("%v is the largest number\n", number2)
	}	else if (number3 > number1) && (number3 > number2){
			fmt.Printf("%v is the largest number\n", number3)
	}	else {
		fmt.Printf("Numbers are equal\n")
	}
}

22. A Go program to spell digits

  // a go program to spell digits with if, else if, else
package main

import "fmt"
func main(){
	var digit int
	fmt.Printf("Enter a digit (0-9): ")
	fmt.Scanf("%v",&digit)

	if (digit == 0){
			fmt.Printf("Zero\n")
	}	else if (digit == 1){
			fmt.Printf("One\n")
	}	else if (digit == 2){
			fmt.Printf("Two\n")
	}	else if (digit == 3){
			fmt.Printf("Three\n")
	}	else if (digit == 4){
			fmt.Printf("Four\n")
	}	else if (digit == 5){
			fmt.Printf("Five\n")
	}	else if (digit == 6){
			fmt.Printf("Six\n")
	}	else if (digit == 7){
			fmt.Printf("Seven\n")
	}	else if (digit == 8){
			fmt.Printf("Eight\n")
	}	else if (digit == 9){
			fmt.Printf("Nine\n")
	}	else {
		fmt.Printf("Not a digit\n")
	}
}

23. switch control statement

- same as c, c++, java, js but only difference you do not use break statement. only run the mateched statement

  // a go program to spell digits with switch statement
package main

import "fmt"
func main(){
	var digit int
	fmt.Printf("Enter a digit (0-9): ")
	fmt.Scanf("%v",&digit)

	switch digit {
	case 0:
		fmt.Printf("Zero\n")
	case 1:
		fmt.Printf("One\n")
	case 2:
		fmt.Printf("Two\n")
	case 3:
		fmt.Printf("Three\n")
	case 4:
		fmt.Printf("Four\n")
	case 5:
		fmt.Printf("Five\n")
	case 6:
		fmt.Printf("Six\n")
	case 7:
		fmt.Printf("Seven\n")
	case 8:
		fmt.Printf("Eight\n")
	case 9:
		fmt.Printf("Nine\n")
	default:
		fmt.Printf("Not a digit\n")
	}

}

24. Loop control statement

in go we have only 1 loop which is for loop; can take form of while loop as weell
it helps us to execute some statements again and again

25. Series related programs

    package main

    import "fmt"
    func main(){

        // series -> 2 + 4 + 6 + 8 + ... N
        var startNumber, endNumber int

        fmt.Printf("Enter the starting number of series: ")
        fmt.Scan(&startNumber)

        fmt.Printf("Enter the last number of series: ")
        fmt.Scan(&endNumber)

        sum := 0
        for i := startNumber; i <= endNumber; i=i+2 {
          sum = sum + i
        }
        fmt.Printf("sum = %v\n",sum)

}

26. break and continue statement

  package main

import "fmt"
func main(){

	// break, continue statement

	for i := 1; i <= 10; i++ {
		if i%2 == 0 {
			continue
		}
		fmt.Printf("%v\n",i)
	}
	for i := 1; i <= 10; i++ {
		if i%2 == 0 {
			break
		}
		fmt.Printf("%v\n",i)
	}

}

27. Functions

28. Arrays & slices data types

array is fixed in Go
var arrayName[size] dataType
only the same data type in one array
var array_name = [length]datatype{values} // here length is defined
array index starts with 0
what if we dont know the size of array then we will use slice; allows us to use dynamic size
append(sliceName, sliceNewValue)

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Go Programming Tutorial

1. Introduction to Go Programming

2. Go Program structure

3. Environment setup

4. First Go Program

5. Tokens - Escape sequences & comments

6. Keywords & Data types

7. Variables

8. Formatting output

9. Constants && Getting User Input

10. Number conversion calculator & number formatting

11. Operators

12. Find the area of triangle and circle

13. Assignment Operator

14. Unary Operator

15. Relational Operator

16. Logical Operator

17. Bitwise Operator

18. if, else if, else control statement

19. A Go program to determine whether a number is even/odd

20. A Go program to find largest number among 3 numbers using relational operators

21. A Go program to find largest number among 3 numbers using Logical operators

22. A Go program to spell digits

23. switch control statement

24. Loop control statement

25. Series related programs

26. break and continue statement

27. Functions

28. Arrays & slices data types

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Go Programming Tutorial

1. Introduction to Go Programming

2. Go Program structure

3. Environment setup

4. First Go Program

5. Tokens - Escape sequences & comments

6. Keywords & Data types

7. Variables

8. Formatting output

9. Constants && Getting User Input

10. Number conversion calculator & number formatting

11. Operators

12. Find the area of triangle and circle

13. Assignment Operator

14. Unary Operator

15. Relational Operator

16. Logical Operator

17. Bitwise Operator

18. if, else if, else control statement

19. A Go program to determine whether a number is even/odd

20. A Go program to find largest number among 3 numbers using relational operators

21. A Go program to find largest number among 3 numbers using Logical operators

22. A Go program to spell digits

23. switch control statement

24. Loop control statement

25. Series related programs

26. break and continue statement

27. Functions

28. Arrays & slices data types

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