CODEWITHSUNDEEP
cpointersgcc-warning
belkka
belkka

Reputation: 273

GCC warning: initialization of 'int32_t *' {aka 'int *'} from 'int' makes pointer from integer without a cast [-Wint-conversion]

Here is a C program:

#include<stdio.h>
#include<stdint.h>


int main() {
    int32_t *ptr = 5;
    printf("ptr is %p\n", ptr);
    printf("++ptr is %p\n", ++ptr);
}

The intention is to initialize a pointer with literal address (e. g. 5) and look how it changes after increment.

gcc produces following warning

warning: initialization of 'int32_t *' {aka 'int *'} from 'int' makes pointer from integer without a cast [-Wint-conversion]
    6 |     int32_t *ptr = 5;
      |                    ^

What is the general way to avoid this warning?

Is "cast" word used as synonym for "explicit cast", so the intended fix is as following?

int32_t *ptr = (int32_t *)5;

Or maybe is there a special syntax for pointer literals?

For the purpose of the program it's possible to declare an additional variable to initialize pointer with its address (like int32_t x, *ptr = &x) or even leave pointer uninitialized, but the question is about this specific warning and initializing pointers with literal values.

Upvotes: 0

Views: 2319

Answers (1)

dbush
dbush

Reputation: 224437

You can silence the warning with an explicit cast as you've shown:

int32_t *ptr = (int32_t *)5;

However, the address 5 is most likely not one your process is allowed to write to and would invoke undefined behavior and would most likely crash.

Upvotes: 1

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