Using variable in System() function?

[Nielyboyken]

Hello

How can I use a variable in the system() function?
Like this:

string a;
cin >> a;
system("ping ", a);

(Just an example).

Of course that code doesn't work, could someone show me an example of how to achieve this?

Thanks for reading,
Niely

[Chervil]

    string a;
    cin >> a;
    string b = "ping " + a;
    system(b.c_str());

[Stewbond]

std::string ip;

cout << "enter an IP address: ";
cin >> ip;

std::string cmd = "ping " + ip;

system( cmd.c_str() );

[Nielyboyken]

Thanks all! :)
Worked like a charm.