Check strtol and make it print the true name in help

1 files changed, 6 insertions, 5 deletions

diff --git a/main.c b/main.c
index 2b90d43..285ce53 100644
--- a/main.c
+++ b/main.c
@@ -1,20 +1,21 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int print_help(void) {
-    printf("Usage: collatz <number>"
-           "\nMade by samuel@yakubos.org\n\n");
+int print_help(char *argv[]) {
+    printf("Usage: %s <number>"
+           "\nMade by samuel@yakubos.org\n\n", argv[0]);
     return 1;
 }
 
 int main(int argc, char *argv[]) {
-    if ( argc < 2 || argc > 2) return print_help();
+    if ( argc < 2 || argc > 2) return print_help(argv);
 
     char *endptr;
     int  int_number = strtol(argv[1], &endptr, 10);
+    if ( *endptr != '\0' ) return print_help(argv);
 
     /* check the number for nonsense */
-    if ( int_number <= 0 ) return print_help();
+    if ( int_number <= 0 ) return print_help(argv);
     unsigned long long long_num = int_number;
 
     int  steps = 0;