bunch of changes

examples/fib.c

@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+
+int n = 35;
+
+int fib(int x) {
+    if (x < 2) {
+      return x;
+    }
+    return fib(x - 1) + fib(x - 2);
+}
+
+int main(int argc, char *argv[]) {
+    if (argc > 1) {
+        char*p;
+
+        errno = 0;
+        long conv = strtol(argv[1], &p, 10);
+
+        // Check for errors: e.g., the string does not represent an integer
+        // or the integer is larger than int
+        if (errno != 0 || *p != '\0' || conv > INT_MAX || conv < INT_MIN) {
+            printf("invalid argument: %s\n", p);
+            exit(1);
+        }
+
+        n = conv;
+    }
+
+    printf("%d\n", fib(n));
+}