_getch() and Ctrl-C

Question

The documentation for _getch() is very clear:

https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/getch-getwch?view=msvc-160

"None of these functions can be used to read CTRL+C"

However this does not seem to be true in the most trivial case.

#include <iostream>  
#include <conio.h>  
#include <windows.h>  
  
int main()  
{  
  
  std::cout << "x to exit\n";  
  while (true) {  
    int c = _getch();  
    std::cout << "KB " << c << '\n';  
    if (c == 'x')  
      return 0;      
  }  
  return 0;  
}  
  

Run this program and it writes "KB 3" for Ctrl-C.

If I don't call _getch() then Ctrl-C is handled as expected.

Answer 1

I agree with @David Lowndes about the docs appearing to be incorrect.

Inside the code for the _getch function the console mode is reset to allow Ctrl+C to be read as input.

Answer 2

Thanks, that's interesting. This is a bit annoying if you are relying on Ctrl-C to call the signal handler. I don't suppose there is any way around this given that the RTL resets the mode. The first thing I did when I found this was check that ENABLE_PROCESSED_INPUT was set in console mode. It did not occur to me that _getch would be so brutal as to reset the lot!

Answer 3

@Martin Lafferty Use Ctrl+Break instead.