Update code sample in README.md

Author: camgunz

README.md

@@ -34,6 +34,10 @@ static bool file_reader(cmp_ctx_t *ctx, void *data, size_t limit) {
     return read_bytes(data, limit, (FILE *)ctx->buf);
 }
 
+static bool file_skipper(cmp_ctx_t *ctx, size_t count) {
+    return fseek((FILE *)ctx->buf, count, SEEK_CUR);
+}
+
 static size_t file_writer(cmp_ctx_t *ctx, const void *data, size_t count) {
     return fwrite(data, sizeof(uint8_t), count, (FILE *)ctx->buf);
 }
@@ -56,7 +60,7 @@ int main(void) {
     if (fh == NULL)
         error_and_exit("Error opening data.dat");
 
-    cmp_init(&cmp, fh, file_reader, file_writer);
+    cmp_init(&cmp, fh, file_reader, file_skipper, file_writer);
 
     if (!cmp_write_array(&cmp, 2))
         error_and_exit(cmp_strerror(&cmp));
@@ -92,13 +96,14 @@ int main(void) {
     if (!cmp_read_str(&cmp, message_pack, &str_size))
         error_and_exit(cmp_strerror(&cmp));
 
-    printf("Array Length: %zu.\n", array_size);
+    printf("Array Length: %u.\n", array_size);
     printf("[\"%s\", \"%s\"]\n", hello, message_pack);
 
     fclose(fh);
 
     return EXIT_SUCCESS;
 }
+
 ```
 
 ## Advanced Usage