Parse command-line args (#26161)

examples/cpp/helloworld/BUILD

@@ -52,6 +52,7 @@ cc_binary(
         "//:grpc++",
         "//examples/protos:helloworld_cc_grpc",
         "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:parse",
     ],
 )
 
@@ -86,5 +87,6 @@ cc_binary(
         "//:grpcpp_admin",
         "//examples/protos:helloworld_cc_grpc",
         "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:parse",
     ],
 )

examples/cpp/helloworld/xds_greeter_client.cc

@@ -21,6 +21,7 @@
 #include <string>
 
 #include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
 
 #include <grpcpp/grpcpp.h>
 
@@ -77,6 +78,7 @@ class GreeterClient {
 };
 
 int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
   GreeterClient greeter(grpc::CreateChannel(
       absl::GetFlag(FLAGS_target), absl::GetFlag(FLAGS_secure)
                                        ? grpc::experimental::XdsCredentials(

examples/cpp/helloworld/xds_greeter_server.cc

@@ -21,6 +21,7 @@
 #include <string>
 
 #include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
 #include "absl/strings/str_cat.h"
 
 #include <grpcpp/ext/admin_services.h>
@@ -101,6 +102,7 @@ void RunServer() {
 }
 
 int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
   RunServer();
   return 0;
 }