How to disable cout output in the runtime?

Question

I often use cout for debugging purpose in many different places in my code, and then I get frustrated and comment all of them manually.

Is there a way

Answer 1

It seems you print debug messages. You could use TRACE within Visual C++/MFC or you just might want to create a Debug() function which takes care of it. You can implement it to turn on only if a distinct flag is set. A lot of programs use a command line parameter called verbose or -v for instance, to control the behavior of their log and debug messages.

Answer 2

You can user cerr - standard output stream for errors for your debug purposes.

Also, there is clog - standard output stream for logging.

Typically, they both behave like a cout.

Example:

cerr << 74 << endl;

Details: http://www.cplusplus.com/reference/iostream/cerr/

http://www.cplusplus.com/reference/iostream/clog/

Answer 3

To supress output, you can disconnect the underlying buffer from cout.

#include <iostream>

using namespace std;

int main(){

    // get underlying buffer
    streambuf* orig_buf = cout.rdbuf();

    // set null
    cout.rdbuf(NULL);

    cout << "this will not be displayed." << endl;

    // restore buffer
    cout.rdbuf(orig_buf);

    cout << "this will be dispalyed." << endl;

    return 0;
}

Answer 4

Don't use cout for debugging purposes, but define a different object (or function, or macro) that calls through to it, then you can disable that function or macro in one single place.

Answer 5

Sure, you can (example here):

int main() {
    std::cout << "First message" << std::endl;

    std::cout.setstate(std::ios_base::failbit);
    std::cout << "Second message" << std::endl;

    std::cout.clear();
    std::cout << "Last message" << std::endl;

    return 0;
}

Outputs:

First message
Last message

This is because putting the stream in fail state will make it silently discard any output, until the failbit is cleared.