Question

How to check whether a string is empty or not in C

Answer 1

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

int main() {
    char s1[10], s2[] = "c++", s3[] = "";
    
    printf("s1 len = %i\n", strlen(s1));
    printf("s2 len = %i\n", strlen(s2));
    printf("s3 len = %i\n", strlen(s3));
    
    printf("s1[0] = %i\n", s1[0] == '\0');
    printf("s2[0] = %i\n", s2[0] == '\0');
    printf("s3[0] = %i\n", s3[0] == '\0');

    printf("s1 = %i\n", strcmp(s1, ""));
    printf("s2 = %i\n", strcmp(s2, ""));
    printf("s3 = %i\n", strcmp(s3, ""));
    
    printf("!*s1 = %i\n", !*s1);
    printf("!*s2 = %i\n", !*s2);
    printf("!*s3 = %i\n", !*s3);
}



/*
run:

s1 len = 0
s2 len = 3
s3 len = 0
s1[0] = 1
s2[0] = 0
s3[0] = 1
s1 = 0
s2 = 99
s3 = 0
*s1 = 1
*s2 = 0
*s3 = 1

*/

 

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