Solve challenge 2

ex02/main.c

@@ -0,0 +1,29 @@
+#include "utils.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+  if (argc < 3) {
+    printf("Usage: %s <hex1> <hex2>\n", argv[0]);
+    return EXIT_FAILURE;
+  }
+
+  unsigned char buf1[512] = {0};
+  size_t len1 = hex_to_bytes(buf1, argv[1]);
+  unsigned char buf2[512] = {0};
+  size_t len2 = hex_to_bytes(buf2, argv[2]);
+
+  if (len1 != len2) {
+    printf("Different lengths!\n");
+    return EXIT_FAILURE;
+  }
+
+  for (size_t i = 0; i < len1; ++i) {
+    unsigned char c = buf2[i] ^ buf1[i];
+    printf("%x", c);
+  }
+  printf("\n");
+
+  return EXIT_SUCCESS;
+}