[quietbritishjim]

> That’s a bit more robust than using strlen(s)+2

strlen wouldn't even be an option if you were formatting something that's not a string e.g.

    int n;
    int prefix_num = 23;
    char *line1 = "line 1";
    char *line2 = "line 2";
    printf("example %d: %n%s\n", prefix_num, &n, line1);
    printf("%*s%s\n", n, "", line2);