Question

I have the following code

#include<stdio.h>
#include<string.h>

int main (void)
{

    unsigned int pqr = 201;
    unsigned int def = 113;

    printf("The values are,%u,%s,%s,%u\n", pqr,"\0","\0",def);
    printf("The values are,%u,%d,%d,%u\n", pqr,atoi("\0"),atoi("\0"),def);


}

The values are,201,,,113
The values are,201,0,0,113

The first printf gives me nothing if the value string is set to NULL and I used format specifier “%S”. How do I achieve the same result using format specifier %d in the second. Currently it gives “0” instead of nothing.

Answer 1

The first printf gives me nothing if the value string is set to NULL and I used format specifier “%S”.

"" is the empty string. "\0" is an empty string with an additional null character. It is not the same as NULL. Passing a null pointer for the s conversion specifier is undefined behavior.

How do I achieve the same result using format specifier %d in the second.

You cannot. printf with %d conversion specification prints an int value; it cannot print nothing.