what is the correct way to handle multiple input command differently in c++?

Question

I have a program that take commands from user and it will process different commands differently. For example:

ADD_STUDENT ALEX 5.11 175
ADD_TEACHER MERY 5.4         


        

Answer 1

Well, it's too late for much chance at upvotes, but you guys got me thinking about this...

For robustness, you could split parsing into two stages: the first stage gets lines, and the second stage takes a line and does something with it.

For the first stage, you can use the getline:

#include 
#include 

void ParseLines(std::istream& source)
{
    while(source)
    {
        // Get a line from the source.
        std::string inputLine;
        std::getline(source, inputLine);

        // Make a stream out of it.
        std::istringstream inputStream(inputLine);
        std::string command;
        inputStream >> command;
        if(inputStream) // Empty or bad line: skip
            HandleCommand(command, inputStream);
    }
}

The second stage handles the command. It could be something direct like this:

void HandleCommand(const std::string& command, std::istringstream& params)
{
    if(command == "ADD_STUDENT")
    {
        float someFloat;
        int someInt;
        params >> someFloat >> someInt;
        // add the student.
    }
    // etc.
}

But I have no shame and would implement a Factory paradigm:

#include 

Haven't tested any of this, but it should be mostly there. Note any bugs in the comments.

P.S. This is highly inefficient and will run slower than a properly designed command parser, however, it should be good enough for most jobs.