C ++解析命令行参数和布尔

Question

So, I'm trying to add something that allows me to use argv to allow three command line inputs.

such that:

./program input.dat (string input) 

so that (I assume) argv[0] = input.dat and argv[1] = string input , argue[2] = file output

...I'm not sure if I'm explaining it right, but this is my best effort. what I want to do is have a command line input that allows me to have like, if it says "encrypt" it makes a bool true, and if I type "decrypt" it sets that bool to false.

Answer 1

bool encrypt;
std::string action(argv[2]);
if (action == "encrypt") {
    encrypt = true;
} else if (action == "decrypt") {
    encrypt = false;
} else {
    // Report invalid argument
}

Answer 2

To do what you're describing:

int main(int argc, char** argv) {
    if (argc < 3) {
        // print usage here and return, since that's what you need.
    }

    const char* filename = argv[1];

    if (!strcmp(argv[2], "encrypt")) {
        // encrypt!
    }
    else if (!strcmp(argv[2], "decrypt")) {
        // decrypt!
    }
    else {
        // error!
    }
}

Or alternatively with strings:

std::string filename = argv[1];
std::string mode = argv[2];
if (mode == "encrypt") { 
    // etc.
}

You can have lots of args, There's nothing to stop you from calling:

./program hi everybody this is a little excessive but just an example

At which point, you'd get called with argc == 12 and, eg, argv[5] pointing to `"a"``.