Self Doubt

Question

1.

#include <stdio.h>

int main() {
    
    int i;
    char a[] = ""; // no tab space in between
    if(printf("%s",a))
    printf("string empty");
    else
    printf("string is not empty");
    return 0;
}

 

Output: string is not empty

 

2.

#include <stdio.h>

int main() {
    
    int i;
    char a[] = " ";  // used a tab space in between
    if(printf("%s",a))
    printf("string empty");
    else
    printf("string is not empty");
    return 0;
}

Output: string empty

 

Why and how so?

Answer 1

Program 1.

Return value of printf() -> No. of characters printed on the standard output

char a[] contains NULL string i.e. the character '\0'.

When printft()  is executed , it prints nothing, ie printf() returns 0 (No. of characters printed are zero). Hence the if body isn't executed.

Program 2.

char a[] contains string of length 1, ie a 'space character'.

When printf() is executed, prints the space character onto the console, returns 1 (No. of characters printed). 'if' condition evaluates to TRUE.