命令行程序选项解析函数—getopt_long

getopt函数只能解析短选项，getopt_long除了接受短选项，还能解析长选项。因此，getopt_long函数在linux命令行程序中使用得最广泛。

 

 1. 函数原型    

  #include

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

 

2. 参数

(1)argc

(2)argv

(3)optstring：短选项字符集合。若只有长选项，则置为空字符串(“”)

(4)longopts：指向struct option数组的第一个元素，结构体option定义如下

struct option

{

  const char *name;  //长选项名称

  int has_arg; //是否有参数no_argument(0)  required_argument(1)  optional_argument(2)

  int *flag; //指定长选项的返回结果：NULL 返回val；非空返回0

  int val; //返回的值或装载flag指向的变量

};

注：struct option 数组最后一个元素用0填充

(5)longindex 非空的话，指向长选项的索引

 

3. 返回值

对短选项，返回对应的选项字符；

对长选项，若flag为NULL，返回val；否则返回0

 

4. 测试

这里只测试长选项，至于短选项的处理则和getopt函数相同

mygetoptlong.c

 
#include
#include

void usage(const char *p);

int main(int argc, char *argv[])
{
    int ch = 0, longindex = 0;
    struct option myoption[] = {
                                 {"input", 1, NULL, 'i'},
                                 {"all", 0, NULL, 'a'},
                                 {"output", 1, NULL, 'o'},
                                 {"version", 0, NULL, 'v'},
                                 {"help", 0, NULL, 'h'},
                                 {NULL, 0, NULL, 0}
                               };
    opterr = 0; // prevent error information to print for unrecognized options
    while( ( ch = getopt_long(argc, argv, "", myoption, &longindex ) ) != -1 )
     {
        switch(ch)
        {
           case 'i':
           case 'o':
                printf("option \"%s\": ", myoption[longindex].name);
                printf("%s\n\n", optarg);
                break;
           case 'a':
           case 'v':
                printf("option \"%s\": \n\n", myoption[longindex].name);
                break;
           case 'h':
                printf("option \"%s\": \n\n", myoption[longindex].name);
                usage(argv[0]);
                break;
           default:
                printf("uncognized option: %c\n\n", optopt);
                usage(argv[0]);
        }
     }
if ( optind < argc )
       {
          printf("\nnon-opotion arguments below:\n");
          while( optind < argc )
            {
                printf("%s\n", argv[optind++]);
            }
       }
    return 0;
}
void usage(const char *p)
{
   printf("Usage: %s [--input infile] [--all] [--output outfile] [--version] [--help] [file]\n\n", p);
}
 

 

执行结果：

$ ./mygetoptlong --input infile --all --output outfile --version --help file

option "input": infile

 

option "all":

 

option "output": outfile

 

option "version":

 

option "help":

 

Usage: ./mygetoptlong [--input infile] [--all] [--output outfile] [--version] [--help] [file]

 

 

non-opotion arguments below:

file