How to pass file path to program as argument if it runs from environment variable? C++

Question

Im making college project to code and decode files. I want it to run from command line something like this:

myapp file_name -code

myapp file_name -decode

How do I get path to file in directory where I opened CMD and how do I save file to same directory? My code if its needed:

int main(int argc, char *argv[]) {
    std::cout << argv[1] << std::endl;
if (argv[2] == "code" || argv[2] == "c") {
    try {
        WriteAllBytes("coded.gau", StringToCharVector(Code(CharVectorToString(ReadAllBytes(argv[1])))));
    } catch (...) {
        std::cout << "Exception!" << std::endl;
    }
} else if (argv[2] == "decode" || argv[2] == "d") {
    try {
        WriteAllBytes("coded.gau", StringToCharVector(Decode(CharVectorToString(ReadAllBytes(argv[1])))));
    } catch (...) {
        std::cout << "Exception!" << std::endl;
    }
}

}

Don't forget about things like getopt to make argument parsing easier and more reliable. This code will crash, hard, if argc isn't at least 3. — tadman
– tadman, Commented Dec 19, 2020 at 11:24
The argv[2] checking is wrong, it is not obvious why you can't debug this. In VS use Project > Properties > Debugging > "Command Arguments". — Hans Passant
– Hans Passant, Commented Dec 19, 2020 at 13:40

Ghasem Ramezani · Accepted Answer · 2020-12-19 11:32:48Z

You can use

Boost.Program_Options:

// Declare the supported options.
po::options_description desc("Allowed options");
desc.add_options()
    ("help", "produce help message")
    ("compression", po::value<int>(), "set compression level")
;

po::variables_map vm;
po::store(po::parse_command_line(ac, av, desc), vm);
po::notify(vm);

Glibc getopt():

while ((c = getopt (argc, argv, "abc:")) != -1)
    switch (c)
      {
      case 'a':
        aflag = 1;
        break;
      case 'b':
        bflag = 1;
        break;
...

See rest of the example: https://www.gnu.org/software/libc/manual/html_node/Example-of-Getopt.html

QCommandLineParser:

QCommandLineParser parser;
parser.setApplicationDescription("Test helper");
parser.addHelpOption();
parser.addVersionOption();
parser.addPositionalArgument("source", QCoreApplication::translate("main", "Source file to copy."));
parser.addPositionalArgument("destination", QCoreApplication::translate("main", "Destination directory."));

Rest of the example: https://doc.qt.io/qt-5/qcommandlineparser.html#details

You can parse it your self, What is your mean by without libraries ? your program already linked to libc which you could use getopt().
If you follow the rule of asking a good question we guide you better than you ask your question chunk by chunk, See this: stackoverflow.com/a/10404524/9248466

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