strcmp crashes when comparing with a malloc array

Question

The strcmp cause the program to crash, Why is that? When removing strcmp it works well, and also with strcpy makes it crash

size_t maxLineLen=1024;
char *line = (char*)malloc(maxLineLen);
while(getline(&line, &maxLineLen,stdin)!= -1){
int h =strlen(line);
for (int i = 0; i < h; i++){
             if(strcmp(line[0], "a") == 0)  {
        printf("a found  %c \n ",line[i]);
            break;
        }

    }

}
return 0;
}

Answer 1

The strcmp function expects a char * for the first argument, but you're passing a char. Similarly with strcpy. This caused undefined behavior.

Your compiler should have given you a warning regarding this.

If what you're trying to do is see if a given character in the string is a, you would do it like this:

if (line[i] == 'a')