Let us create a new console project App7 and replace code inside main.cpp file with following code:

#include <iostream>

int main() {
    const double pi = 3.1415926535897932384626433832795;
    double radius   = 20.0;
    double perimeter= 0.0;
    perimeter = 2 * pi * radius;
    std::cout << "Perimeter = " << perimeter << std::endl;
    return 0;
}

Ensure that Debug target is selected in compiler toolbar and then compile it by clicking compile button. App7 will be compiled for debugging.

Before we ask GDB to debug we have to create breakpoints for it. After the code is typed in editor window Code::Blocks will look similar to the following screenshot.

To set a breakpoint move cursor to the left side of editor window next to the indicated line numbers. Now the cursor will change to a right-tilted cursor. Pause mouse and left-click. A breakpoint will be set there and will be indicated by a red circle. The following screenshot shows that a breakpoint...