// getopt_long.cpp
// Using getopt_long

#include <iostream>
#include <cstdlib>
#include <getopt.h>
using namespace std;

const char* program_name;

void print_usage(ostream& os, int exit_code) {
os << "Usage : %s options [ inputfile ... ]\n" << program_name << endl;
os << " -h --help Display this usage information." << endl
<< " -o --output filename Write output to file." << endl
<< " -v --verbose Print verbose messages." << endl;
exit (exit_code);
}

int main(int argc, char** argv) {
int next_option;

const char* const short_options = "ho:v";

const struct option long_options[] = {
{ "help", 0, NULL, "h" },
{ "output", 1, NULL, "o" },
{ "verbose", 0, NULL, "v" },
{ NULL, 0, NULL, 0 }
};

const char* output_filename = NULL;

int verbose = 0;

program_name = argv[0];

do {
next_option = getopt_long (argc,argv,short_options,long_options,NULL);

switch (next_option) {
case 'h':
print_usage(cout, 0);

case 'o':
output_filename = optarg;
break;

case 'v':
verbose = 1;
break;

case '?':
print_usage (cerr, 1);

case -1:
break;

default:
abort();
}
} while (next_option != -1);

if (verbose) {
for (int i = optind; i < argc; i++)
cout << "Argument : " << argv[i] << endl;
}

return 0;
}

I got a series of error messages , which I shall post here.
They are...

$ g++ -g getopt_long.cpp -Wall
getopt_long.cpp: In function `int main(int, char**)':
getopt_long.cpp:29: invalid conversion from `const char*' to `int'
getopt_long.cpp:29: invalid conversion from `const char*' to `int'
getopt_long.cpp:29: invalid conversion from `const char*' to `int'

Compilation exited abnormally with code 1 at Thu Aug 28 09:32:27

I don't know what are the messages.
I tried the same code with c, and it compiled with a series of warnings. I got the code form Advanced Linux Programming, and I want to use the getopt in a C++ program of mine.

Thx for any help.

your problem lies here, corrections in red.
if you want a character then enclose it in ' not in ", double quotes produce null terminated strings. also please use code tags, makes the code a lot easier to read

Thank you very very much, kev82. I did not notice it and was very frustrated with this error.

Ok, what do you mean by code tags?

I use emacs, and it automatically formats the code, and when I cut and pasted it into konqueror, the format was gone. Is this what you were referring to?

i meant on the forum, you can use different tags to keep the code formatted correctly, instead of losing your formatting, makes it much easier for everyone here to read. http://www.linuxquestions.org/questi...&action=bbcode