clarify str(1) behavior

str/str.c

@@ -31,6 +31,7 @@ static struct {
 int main(int argc, char *argv[]){
 	int ctype;
 	int i;
+	int r;
 
 	if(argc < 3){
 usage:		fprintf(stderr, "Usage: %s [type] [string...]\n",
@@ -44,10 +45,12 @@ usage:		fprintf(stderr, "Usage: %s [type] [string...]\n",
 			goto pass;
 	goto usage;
 
-pass:	for(argv += 2; *argv != NULL; ++argv)
+pass:	for(argv += 2, r = 1; *argv != NULL; ++argv)
 		for(i = 0; argv[0][i] != '\0'; ++i)
 			if(!ctypes[ctype].f(argv[0][i]))
 				return 1;
+			else
+				r = 0;
 
-	return 0;
+	return r;
 }