c++ - 在 C++ 中使用 getopt 时打印默认参数

Question

static struct option long_options[] =
{
     {"r",   required_argument,  0, 'r'},
     {"help",        no_argument,        0, 'h'},
     {0, 0, 0, 0}
};


int option_index = 0;
char c;
while((c = getopt_long(argc, argv, "r:h", long_options, &option_index)) != -1)
{
    switch(c)
    {
        case 'r':
            break;
        case 'h':
            return EXIT_SUCCESS;
    }
}

我如何使 h 成为默认参数，这样如果这个程序在没有任何参数的情况下运行，它就像是使用 -h 运行的一样？

Answer 1

也许尝试这样的事情:

static struct option long_options[] =
{
     {"r",    required_argument,  0, 'r'},
     {"help", no_argument,        0, 'h'},
     {0, 0, 0, 0}
};

int option_index = 0;
char c = getopt_long(argc, argv, "r:h", long_options, &option_index);
if (c == -1)
{
    // display help...
    return EXIT_SUCCESS;
}

do
{
    switch(c)
    {
        case 'r':
            break;

        case 'h':
        {
            // display help...
            return EXIT_SUCCESS;
        }
    }

    c = getopt_long(argc, argv, "r:h", long_options, &option_index);
}
while (c != -1);

或者这个:

static struct option long_options[] =
{
     {"r",    required_argument,  0, 'r'},
     {"help", no_argument,        0, 'h'},
     {0, 0, 0, 0}
};

int option_index = 0;
char c = getopt_long(argc, argv, "r:h", long_options, &option_index);
if (c == -1)
    c = 'h';

do
{
    switch(c)
    {
        case 'r':
            break;

        case 'h':
        {
            // display help...
            return EXIT_SUCCESS;
        }
    }

    c = getopt_long(argc, argv, "r:h", long_options, &option_index);
}
while (c != -1);