How do we read it: *((int *)ptr) ?

Question

C Pointer

Answer 1

A void pointer points to a memory location but doesn't contain any information about the type of data it points to. So it doesn't know if the memory location it points to is an integer, a character, a float or whatever. *ptr dereferences the pointer (=gets the value at the memory location the pointer points to). (int*) tells the compiler to handle the value as an integer (type casting from a void pointer to an int pointer)

Answer 2

ptr is a void pointer, so a pointer that hasn't specified which type it points to.

Before you access it you need to cast it into a type, just like sometimes you convert a string to an int

(int *) ptr
// roughly like (int)some_char

And to access what the pointer points to, you need the star as always, so *((int *)ptr).

(btw: You don't need the outer set of parentheses.)

Answer 3

~ swim ~ Look at the code OP posted...

Answer 4

#include <stdio.h>

int main() {
int x = 33;
float y = 12.4;
char c = 'a';
void *ptr;

ptr = &x;
printf("void ptr points to %d\n", *((int *)ptr));
ptr = &y;
printf("void ptr points to %f\n", *((float *)ptr));
ptr = &c;
printf("void ptr points to %c", *((char *)ptr));

return 0;
}

Answer 5

ptr is a variable of type *int.
ptr is a pointer too.

So ptr points to a pointer pointing to an integer I guess.

Correct me if I am wrong.

Answer 6

Ok all, thanks a lot. I could figure out it now.

Answer 7

Anna and HonFu can you please help with this
https://www.sololearn.com/Discuss/1689859/?ref=app

Answer 8

My brain get an error here: *((int *)ptr)

Answer 9

What is the problem? It's okay!

Answer 10

*AsterisK* : just try to search at: https://www.ioccc.org, i think it is from.

Answer 11

*(int*) p
Explain