[zz]使用 Google gflags 简化命令行参数处理

（本文章仅适用于C++程序）
写服务程序时，如果需要提供命令行参数。传统的方法是手工解析argv参数，或者使用getopt函数。两种方法都比较费劲。使用Google gflags可以大大简化命令行参数处理。

安装gflag

从官方地址http://code.google.com/p/google-gflags/下载gflags并安装。比如我下载的是1.5版本。

[yichi@yichi tmp]$ wget http://google-gflags.googlecode.com/files/gflags-1.5.tar.gz

[yichi@yichi tmp]$ tar zxvf gflags-1.5.tar.gz

[yichi@yichi tmp]$ cd gflags

[yichi@yichi gflags-1.5]$ ./configure –prefix=$HOME/google-library

[yichi@yichi gflags-1.5]$ make j=4 & make install

使用gflags

示例代码下载地址：http://www.faithbee.com/wp-content/uploads/2011/05/gflags-sample.tar.bz2

main.cc

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// Copyright (c) 2011, D-Media Communication Technology Inc. // All rights reserved. // // // --- // Author: Yichi Zhang <zyichi@gmail.com> // // File content description here   #include "server.h"   #include <google/gflags.h>   #include <string>   #include <stdio.h>   DEFINE_bool(memory_pool, false, "If use memory pool"); DEFINE_bool(daemon, true, "If started as daemon"); DEFINE_string(module_id, "", "Server module id");   DEFINE_int32(http_port, 80, "HTTP listen port"); DEFINE_int32(https_port, 443, "HTTPS listen port");   int main(int argc, char** argv) {   ::google::ParseCommandLineFlags(&argc, &argv, true);     // XXX NOTE: Should add 'FLAGS_' prefix.   printf("Server module id: %s\n", FLAGS_module_id.c_str());     if (FLAGS_daemon) {     printf("Run as daemon: %d\n", FLAGS_daemon);   }   if (FLAGS_memory_pool) {     printf("Use memory pool: %d\n", FLAGS_daemon);   }     Server server;     return 0; }

server.h

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// Copyright (c) 2011, D-Media Communication Technology Inc. // All rights reserved. // // // --- // Author: Yichi Zhang <zyichi@gmail.com> // // File content description here   #include <google/gflags.h>   #include <stdio.h>   // Declare, defined in 'main.cc'. DECLARE_int32(http_port); DECLARE_int32(https_port);   class Server {  public:   Server() {     // XXX NOTE: Should add 'FLAGS_' prefix.     printf("HTTP listen port: %d\n", FLAGS_http_port);     printf("HTTPS listen port: %d\n", FLAGS_https_port);   }   virtual ~Server() {}    private:   ; };

编译示例程序

[yichi@yichi gflags-sample]$ g++ -o gflags-sample main.cc -I $HOME/google-library/include -L $HOME/google-library/lib -lgflags

运行示例程序

带参数运行

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample

Server module id:

Run as daemon: 1

HTTP listen port: 80

HTTPS listen port: 443

带参数运行，使用等号赋值

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample -module_id="server_007" -daemon=true -http_port=8080 -https_port=4443

Server module id: server_007

Run as daemon: 1

HTTP listen port: 8080

HTTPS listen port: 4443

带参数运行，使用空格分割参数和值

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample -module_id "server_007" -daemon true -http_port 8080 -https_port 4443

Server module id: server_007

Run as daemon: 1

HTTP listen port: 8080

HTTPS listen port: 4443

显示帮助

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample –help

gflags-sample: Warning: SetUsageMessage() never called

Flags from main.cc:

-daemon (If started as daemon) type: bool default: true

-http_port (HTTP listen port) type: int32 default: 80

-https_port (HTTPS listen port) type: int32 default: 443

-memory_pool (If use memory pool) type: bool default: false

-module_id (Server module id) type: string default: ""

参考资料

Google gflags官方文档：http://google-gflags.googlecode.com/svn/trunk/doc/gflags.html