在C ++中传递命令行参数

Question

I've been trying to learn how to extend Python 3 with C++, and I was recommended using Boost. I believe I've followed the procedure of setting up Boost::Python correctly so far, and I have the following code from here (saved as example.cpp) which builds successfully:

#include <boost/regex.hpp>
#include <iostream>
#include <string>

int main()
{
    std::string line;
    boost::regex pat( "^Subject: (Re: |Aw: )*(.*)" );

    while (std::cin)
    {
        std::getline(std::cin, line);
        boost::smatch matches;
        if (boost::regex_match(line, matches, pat))
            std::cout << matches[2] << std::endl;
    }
}

The instructions suggested testing this worked by creating a text file called jayne.txt and saving data inside it, and then executing the program from a command prompt and passing in the path to the file as an argument. I don't know C++ very well at all and I've been having difficulties with this.

I've tried opening the command prompt, and running "path/to/example.cpp" < "path/to/jayne.txt" and "path/to/example.cpp" "path/to/jayne.txt", both from a regular command prompt and from Visual Studio Command Prompt. I should be getting output somewhere, but all that happens is that it opens the program in Visual Studio if it's not already open.

I'm working with MVSC++ 2010 in Windows 7.

Answer 1

C++ is a compiled language - thus, in order to run a program, you need to run the compiled version ( .exe ) rather than the source code ( .cpp ).

When you type "path/to/example.cpp" at the command line, it's opening the source code. Find the actual executable from building your code (generally it's located in a build or Debug folder for MSVC) and run that on the command line and the < operator should work fine.