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2024-03-21-getopt_long

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getopt_long

1
int getopt_long(int argc, char * const argv[], const char *optstring, const struct option *longopts, int *longindex);

  • argc和argv是main方法的入参，argc是长度，argv是地址数组指针

  • optstring是短选项字符串格式

    • 形式 a:bc::， b表示只有一个字符，没有参数；a:表示a后面可以加一个参数；c::表示参数可选，但是如果带参数不能有空格 -c100
    • eg：-a 200 b -c100

  • longopts是长选项结构体

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    struct option 
    {  
         const char *name;  
         int         has_arg;  
         int        *flag;  
         int         val;  
    };  
    eg:
     static struct option longOpts[] = {
          { "daemon", no_argument, NULL, 'D' },
          { "dir", required_argument, NULL, 'd' },
          { "out", required_argument, NULL, 'o' },
          { "log", required_argument, NULL, 'l' },
          { "split", required_argument, NULL, 's' },
          { "http-proxy", required_argument, &lopt, 1 },
          { "http-user", required_argument, &lopt, 2 },
          { "http-passwd", required_argument, &lopt, 3 },
          { "http-proxy-user", required_argument, &lopt, 4 },
          { "http-proxy-passwd", required_argument, &lopt, 5 },
          { "http-auth-scheme", required_argument, &lopt, 6 },
          { "version", no_argument, NULL, 'v' },
          { "help", no_argument, NULL, 'h' },
          { 0, 0, 0, 0 }

  • name 是长选项

  • val是短选项

  • has_arg 是有没有参数

    • no_argument 无参数，
    • required_argument 有参数，且格式为 –o 100 或者–out=100
    • optional_argument有参数，格式只能为–out=100

  • flag参数有两个意思

    • 如果是NULL，命中长选项时返回短短选项字符串
    • 如果不为NULL，命中长选项时返回0，flag=短选项值

  • longindex longopts数组中匹配到的option位置

  • 全局变量

    • optarg：表示当前选项对应的参数值。
    • optind：表示的是下一个将被处理到的参数在argv中的下标值。
    • opterr：如果opterr = 0，在getopt、getopt_long、getopt_long_only遇到错误将不会输出错误信息到标准输出流。opterr在非0时，向屏幕输出错误。
    • optopt：表示没有被未标识的选项。

  • 返回值

    • 如果短选项找到，那么将返回短选项对应的字符。
    • 如果长选项找到，如果flag为NULL，返回val。如果flag不为空，返回0
    • 如果遇到一个选项没有在短字符、长字符里面。或者在长字符里面存在二义性的，返回“？”
    • 如果解析完所有字符没有找到（一般是输入命令参数格式错误，eg： 连斜杠都没有加的选项），返回“-1”
    • 如果选项需要参数，忘了添加参数。返回值取决于optstring，如果其第一个字符是“：”，则返回“：”，否则返回“？”。

      DEMO

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      //
      // Created by juneleo on 2022/12/29.
      //



      #include<stdio.h>
      #include <getopt.h>
      #include<iostream>
      #include<string>
      #include<stdlib.h>
      using namespace std;

      void showUsage() {
          //cout << "Usage: " << PACKAGE_NAME << " [options] URL ..." << endl;
          cout << "Options:" << endl;
          cout << " -d, --dir=DIR              The directory to store downloaded file." << endl;
          cout << " -o, --out=FILE             The file name for downloaded file." << endl;
          cout << " -l, --log=LOG              The file path to store log. If '-' is specified," << endl;
          cout << "                            log is written to stdout." << endl;
          cout << " -D, --daemon               Run as daemon." << endl;
          cout << " -s, --split=N              Download a file using s connections. s must be" << endl;
          cout << "                            between 1 and 5. If this option is specified the" << endl;
          cout << "                            first URL is used, and the other URLs are ignored." << endl;
          cout << " --http-proxy=HOST:PORT     Use HTTP proxy server. This affects to all" << endl;
          cout << "                            URLs." << endl;
          cout << " --http-user=USER           Set HTTP user. This affects to all URLs." << endl;
          cout << " --http-passwd=PASSWD       Set HTTP password. This affects to all URLs." << endl;
          cout << " --http-proxy-user=USER     Set HTTP proxy user. This affects to all URLs" << endl;
          cout << " --http-proxy-passwd=PASSWD Set HTTP proxy password. This affects to all URLs." << endl;
          cout << " --http-auth-scheme=SCHEME  Set HTTP authentication scheme. Currently, BASIC" << endl;
          cout << "                            is the only supported scheme." << endl;
          cout << " -v, --version              Print the version number and exit." << endl;
          cout << " -h, --help                 Print this message and exit." << endl;
          cout << "URL:" << endl;
          cout << " You can specify multiple URLs. All URLs must point to the same file" << endl;
          cout << " or a download fails." << endl;
          cout << "Examples:" << endl;
          cout << " Download a file by 1 connection:" << endl;
          cout << "  aria2c http://AAA.BBB.CCC/file.zip" << endl;
          cout << " Download a file by 2 connections:" << endl;
          cout << "  aria2c -s 2 http://AAA.BBB.CCC/file.zip" << endl;
          cout << " Download a file by 2 connections, each connects to a different server." << endl;
          cout << "  aria2c http://AAA.BBB.CCC/file.zip http://DDD.EEE.FFF/GGG/file.zip" << endl;
          cout << "Reports bugs to <tujikawa at rednoah dot com>" << endl;
      }

      int main(int argc, char* argv[]) {
          bool stdoutLog = false;
          string logfile;
          string dir;
          string ufilename;
          int split = 0;
          bool daemonMode = false;
          int c;


          while(1) {
              int optIndex = 0;
              int lopt;
              static struct option longOpts[] = {
              { "daemon", no_argument, NULL, 'D' },
              { "dir", required_argument, NULL, 'd' },
              { "out", required_argument, NULL, 'o' },
              { "log", required_argument, NULL, 'l' },
              { "split", required_argument, NULL, 's' },
              { "http-proxy", required_argument, &lopt, 1 },
              { "http-user", required_argument, &lopt, 2 },
              { "http-passwd", required_argument, &lopt, 3 },
              { "http-proxy-user", required_argument, &lopt, 4 },
              { "http-proxy-passwd", required_argument, &lopt, 5 },
              { "http-auth-scheme", required_argument, &lopt, 6 },
              { "version", no_argument, NULL, 'v' },
              { "help", no_argument, NULL, 'h' },
              { 0, 0, 0, 0 }
          };
              c = getopt_long(argc, argv, "Dd:o:l:s:vh", longOpts, &optIndex);
              printf("返回值： %c\n",c);
              if(c == -1) {
              break;
          }
              switch(c) {
              case 0:{
              switch(lopt) {
              case 1: {
              printf("1: %s\n",optarg);
              break;
          }
              case 2:
              printf("2: %s\n",optarg);
              break;
              case 3:
              printf("3: %s\n",optarg);
              break;
              case 4:
              printf("4: %s\n",optarg);
              break;
              case 5:
              printf("5: %s\n",optarg);
              break;
              case 6:
              printf("6: %s\n",optarg);
              break;
          }
              break;
          }
              case 'D':
              printf("D: %s\n",optarg);
              break;
              case 'd':
              printf("d: %s\n",optarg);
              break;
              case 'o':
              printf("o: %s\n",optarg);
              break;
              case 'l':
              printf("l: %s\n",optarg);
              break;
              case 's':
              printf("s: %s\n",optarg);
              break;
              case 'v':
              printf("s: %s\n",optarg);
              //showVersion();
              exit(0);
              case 'h':
              showUsage();
              exit(0);
              default:
              showUsage();
              exit(1);
          }
          }
              return 0;
          }

      测试

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      ./getopt_test --out=file.txt --dir=/Users/juneleo/ --http-proxy=192.168.0.0       
      返回值： o
      o: file.txt
      返回值： d
      d: /Users/juneleo/
      返回值： 
      1: 192.168.0.0