Reverse every word in a string (should handle space)

Question

Examples:

char test1[] = \"               \";
char test2[] = \"   hello  z\";
char test3[] = \"hello world   \";
char test4[] = \"x y z \";

Answer 1

In-place, ANSI C89.

#include 
#include 

void reverse(char *s) {
    int i = 0, j, k;
    while (1) {
        while (isspace(s[i])) i++;
        if (!s[i]) return;
        for (j = i; !isspace(s[j]) && s[j] != '\0'; j++);
        for (k = 0; k < (j - i) / 2; k++) {
            char t = s[i + k];
            s[i + k] = s[j - k - 1];
            s[j - k - 1] = t;
        }
        i = j;
    }
}

int main(int argc, char**argv) {
    if (argc != 2) return 1;
    reverse(argv[1]);
    printf("%s\n", argv[1]);
    return 0;
}