give error message c++ code example

Example 1: c++ windows error message

// A single line of C-code needed
MessageBox(NULL,"An error has occurred because you didn't use this program correctly!", "Error!", MB_OK);

Example 2: c++ message box error

// A single line of C-code needed
MessageBox(NULL, "An error has occurred!", "Title!", MB_ICONERROR | MB_OK);