Print version info on -v and --version

src/zopfli/zopfli.h

@@ -27,6 +27,8 @@ Author: [email protected] (Jyrki Alakuijala)
 extern "C" {
 #endif
 
+#define ZOPFLI_VERSION "1.0.1"
+
 /*
 Options used throughout the program.
 */

src/zopfli/zopfli_bin.c

@@ -141,6 +141,10 @@ static char StringsEqual(const char* str1, const char* str2) {
   return strcmp(str1, str2) == 0;
 }
 
+static void ShowVersion() {
+  fprintf(stderr, "zopfli version %s\n", ZOPFLI_VERSION);
+}
+
 int main(int argc, char* argv[]) {
   ZopfliOptions options;
   ZopfliFormat output_type = ZOPFLI_FORMAT_GZIP;
@@ -178,11 +182,20 @@ int main(int argc, char* argv[]) {
           "  --gzip        output to gzip format (default)\n"
           "  --zlib        output to zlib format instead of gzip\n"
           "  --deflate     output to deflate format instead of gzip\n"
-          "  --splitlast   ignored, left for backwards compatibility\n");
+          "  --splitlast   ignored, left for backwards compatibility\n"
+          "  --version     show version and exit\n");
+      return 0;
+    }
+    else if (StringsEqual(arg, "--version")) {
+      ShowVersion();
       return 0;
     }
   }
 
+  if (options.verbose) {
+    ShowVersion();
+  }
+
   if (options.numiterations < 1) {
     fprintf(stderr, "Error: must have 1 or more iterations\n");
     return 0;