#include <stdio.h>

int main (void) {

    char c[] = "I - need - to - do - this - break",
        *p = c;
    int in = 0;

    while (*p) {
        if (*p == ' ' || *p == '-') {
            if (in) {
                char current = *p;
                *p = 0;
                puts (c);
                *p = current;
            }
            in = 0;
        }
        else {
            in = 1;
        }
        p++;
    }

    if (in)
        puts (c);
}

$ ./bin/incremental
I
I - need
I - need - to
I - need - to - do
I - need - to - do - this
I - need - to - do - this - break