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25 changes: 25 additions & 0 deletions assignment7.txt
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1.
The difference between ++*P, *p++ and *++p is that:
++*P increases the value of *p by one
*p++ moves up the location of the pointer by one
*++p will do exactly what ++*p does
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The expression ++*p has two operators of same precedence, so compiler looks for associativity. Associativity of operators is right to left. Therefore the expression is treated as ++(*p). The expression *p++ is treated as *(p++) as the precedence of postfix ++ is higher than *. The expression *++p has two operators of same precedence, so compiler looks for associativity. Associativity of operators is right to left. Therefore the expression is treated as *(++p).


2.
Yes, the order is guaranteed
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The simple answer to this question is neither, actually. C doesn’t always evaluate left-to-right or right-to-left. Generally, function calls are evaluated first, followed by complex expressions and then simple expressions.


3.
For fuction parameters
for dynamic programming
Pointer enables you to do things that are otherwise impossible, it also speeds up the operation
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right!


4.
4.1 invalid because b and c are undeclared.
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it's just a string, which is a character array, so the answer is char*.

4.2 invalid because of undeclared variables.
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This is actually valid! "xyz" is just an array of characters, so the "xyz"[1] is just accessing "y". Then you just subtract 'y' from it to get 0. This is because, if you can recall, a char is just a value mapped to a character!

4.3 I am not sure what this means.
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'\0' is just a NULL terminator and by definition, NULL is equal to 0. So this would evaluate as true, which is 1 in C.

4.4 10 because the pointer of a string prints the first number.
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right! 💯

4.5 10 because a[0] = 10.
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Close! for this question, we're just looking for the data type, so it actually returns the type int*. Recall that a[0] would be of type int and the ampersand just returns the memory address. So &a[0] would return the pointer to the address (since a pointer is basically an address, which is why all pointers are 8 bytes no matter what they're pointing to), which would be of type int*.

4.6 12 because a = 10 and *p = a + 2.
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hm, not quite! Since a is a pointer to the first element of the array, the increment by 2 would move the pointer two spots over to 12. so 12 is the answer.

4.7 invalid because p has not been declared although *p is.
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The answer is actually int** for the a similar reason as number 5. The address of p returns a pointer to the address, but since p is of type int*, that means it will return the memory address of where the memory address is stored - in other words, a pointer to a pointer.

4.8 ello because argv *argv is moved up one location it will not print the h.
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not quite! It's actuallychar*. This is because the * in *++argv dereferences the char** argv, leading to char **. The incrementing actually does nothing. In the same way that int x = 1; ++x would still be an int!

4.9 I am not sure what this will output.
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Functions in C are actually just pointers to a spot in the program where some code exists. Just like you've been creating pointers to structs, strings, and arrays, you can point a pointer at a function too. The main use for this is to pass "callbacks" to other functions, or to simulate classes and objects. In this exercise we'll do some callbacks, and in the next one we'll make a simple object system.

The format of a function pointer goes like this:

int (*POINTER_NAME)(int a, int b)

So the answer is actually int(*)(int, char**). All you needed to do was evaluate the data types of the &main. Since & returns the memory address, main's data type would change from int to int*. Since argc and argv are just the parameters, they would remain the same data types. So the final answer is int(*)(int, char**).

4.10 10 because that is the size of the string.
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close - Like I said in class, this is just a definition question, so the answer is 8 because pointers always allocate 8 bytes.

20 changes: 20 additions & 0 deletions reverse.c
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#include <stdio.h>
#include <string.h>

void swap() {

char string[50];
printf("Enter your string");
fgets(string, 50, stdin);

char *stringPtr = string;
char *reverseString = &string[strlen(string)];
}

int main() {
while (*stringPtr != *reverseString) {
printf("%c", *(--reverseString)); }

printf("\n");
return 0;
}