Monthly Archives: April 2017

VirtualBox on Windows: Stuck in capture mode as the keyboard does not have a right Ctrl button 1

 in Virtualization  tagged capture mode / HOST KEY COMBINATION / virtualbox by

Recently, we got a laptop that did not have a right Ctrl button and we found out after we started a VM with no Guest Additions installed.
Because of these two factors we could not escape the VM capture mode and return to the host OS.

To resolve the issue, we pressed Alt+Ctrl+Del to force the window to escape by entering that specialised Windows security screen and the hit Cancel.
Then, we went to the VirtualBox window and did the following procedure to change the button that allows you to escape the capture mode.

From the VirtualBox Window menu we went to: File –> Preferences –> Input and then clicked on the box next to HOST KEY COMBINATION and then typed the key we wanted to use.

C/C++: How do you set GDB debug flag (-g) with cmake? 1

 in C / C++ / Programming  tagged cmake / debug / debug metadata / gdb / RelwithDebInfo / symbol table by

Solution 1: Modify the CMakeLists.txt file

Add the following line to your CMakeLists.txt file to set the compilation mode to Debug (non-optimized code with debug symbols):

set(CMAKE_BUILD_TYPE Debug)

Add the following line to your CMakeLists.txt file to set the compilation mode to RelWithDebInfo (optimized code with debug symbols):

set(CMAKE_BUILD_TYPE RelWithDebInfo)

Solution 2: Add a command line argument to your cmake command:

Modify as follows your cmake command to set the compilation mode to Debug (non-optimized code with debug symbols):

cmake -DCMAKE_BUILD_TYPE=Debug <path and other arguments>

Modify as follows your cmake command to set the compilation mode to RelWithDebInfo (optimized code with debug symbols):

cmake -DCMAKE_BUILD_TYPE=RelWithDebInfo <path and other arguments>

Bonus material:

The difference between Debug and RelwithDebInfo modes is that RelwithDebInfo optimizes the code similarly to the behavior of Release mode. It produces fully optimized code, but also creates the symbol table and the debug metadata to give the debugger as much input as it is possible to map the execution back to the original code at any time.

Code build with RelwithDebInfo mode should not have it’s performance degraded in comparison to Release mode, as the symbol table and debug metadata that are generated do not live in the executable code section, so they should not affect the performance when the code is run without a debugger attached.

C++ How to make cout not use scientific notation

 in C++  tagged C++ / cout / fixed / I/O manipulator / scientific notation / std::fixed by

To force cout to print numbers exactly as they are and prevent it from using the scientific notation, we can use the std::fixed I/O manipulator as follows

#include <iostream>

using namespace std;

int main()
{
    std::cout << "The number 0.0001 in fixed:      " << std::fixed << 0.0001 << endl
              << "The number 0.0001 in default:    " << std::defaultfloat << 0.0001 << endl;

    std::cout << "The number 1000000000.0 in fixed:      " << std::fixed << 1000000000.0 << endl
              << "The number 1000000000.0 in default:    " << std::defaultfloat << 1000000000.0 << endl;
return 0;
}

Output

The number 0.0001 in fixed:      0.000100
The number 0.0001 in default:    0.0001
The number 1000000000.0 in fixed:      1000000000.000000
The number 1000000000.0 in default:    1e+09