Printing pointer to int in printf ( )

**adi_K** · 01-27-2016

Hello to All,
I am new to programming & learning, I am trying( in wrong way)to print the content of pointer to int.

what i have done, i have assigned pnum the starting address of const int 345;( which goes with warning in gcc compiler & need (int*) cast in VSexpress edition.

later on I pass pnum to C-legendary printf(), strangely it prints the number 345 , instead of address.

i have consulted many on-line docs & K&R C book , but could not understand what is happening beneath.

Code:

main() {
 int *pnum;
 pnum = 345; // Assign pnum start address of const int 345

printf("\n value stored in pnum %d " , pnum); // it prints 345 instead of address.

// printf("\n Value stored in *pnum %d" ,*pnum); uncomment to crash the program.

return 0;
}

Theoretically it should print the address not content. forum members are requested to enlighten new learner like me

Thanks
Adi

**laserlight** · 01-27-2016

I suggest that you try:

Code:

#include <stdio.h>

int main(void)
{
    int num = 345;
    int *pnum;
    pnum = &num;
    printf("value stored in pnum: %p\n", (void*)pnum);
    printf("value stored at what pnum points to: %d\n", *pnum);
    return 0;
}

Observe that I:

Included the relevant header.
Declared main as returning an int, and explicitly stated that it takes no arguments with void as the parameter list.
Indented the code properly.
Declared an int with a value of 345.
Caused pnum to point to that int.
Printed the value of pnum (i.e., an address) with %p, casting pnum to void* to match.
Printed the value of what pnum points to (i.e., an int) with %d.

**adi_K** · 01-27-2016

Thank you ,laserlight for help,I wish i had been more expressive in explaining the problem initially.In plain English I am trying to assign the address of integer literal 345.In fact I am trying to do something on the line, like pnum = &(345); // which is illegal.However 345 is stored (either on stack or on heap ,C implementation is silent where literals are stored ) in memory.However statement like pnum = 345; (with implicit conversion) results in storing of starting address of location where 345 is stored.So technically speaking after this assignment ,content of pnum should be starting location of 345. similar on the line of char *ps = "My string";in fact statement like *pnum =345; also result in access violation.Documentation for printf() states , that function prints the value of argument.From the result of printf(), it looks that we have assigned 345 to pnum ( after appropriate casting), not the address of 345 literal , I dont know what is happening actually.experienced programmer like you can definetly throw light on subject.thanks Adi

**laserlight** · 01-27-2016