Thread: How come this works?

Code:

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

int main(void)
{
    int i;
    char str1[] = "abcdefghijklm...";
    char str2[100];

    for (i = 0; str1[i]; i++)
        str2[i] = str1[i];

    str2[i] = '\0';

    printf("%s\n", str2);

    return 0;
}

Because when str[i] hits a null ('\0', 0x00, %00, \000, 0) than it will break the loop, because it is 0. The middle statement is the check statement, like the portion inside a while(), execution occurs while it is non-zero.

Though kermit's latter example with the explicit compare to '\0' is clearer, having an implicit test for the '\0' character is a popular idiom in C and should be easily recognisable. The code could also be written as:

Code:

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

int main(void)
{
    int i = 0;
    char str1[] = "abcdefghijklm...";
    char str2[100];

    while (str2[i] = str1[i++]);

    printf("%s\n", str2);

    return 0;
}