Why console cannot catch mouse event after using function system()? - c

Question

When I use the function system(), I cannot catch any mouse event.
I have already know system() function is a shell command, but why using this command will block catching mouse event?
#include <windows.h>
#include <stdio.h>
int main()
{
HANDLE ConsoleWin;
INPUT_RECORD eventMsg;
DWORD Pointer;
//system("mode con cols=140 lines=40"); //after using this function，I cannot catch any mouse event
while (1)
{
ConsoleWin = GetStdHandle(STD_INPUT_HANDLE);//Get the console window
ReadConsoleInput(ConsoleWin, &eventMsg, 1, &Pointer);//Read input msg
if (eventMsg.EventType == MOUSE_EVENT && eventMsg.Event.MouseEvent.dwButtonState == FROM_LEFT_1ST_BUTTON_PRESSED) {
printf("Left button clicked.");
}
else if (eventMsg.EventType == MOUSE_EVENT && eventMsg.Event.MouseEvent.dwButtonState == RIGHTMOST_BUTTON_PRESSED) {
printf("Right button clicked.");
}
}
return 0;
}

Answer 1

system() executes a new cmd.exe which resets many console flags. After each "system" you should restore console options this way:
DWORD mode;
GetConsoleMode(ConsoleWin, &mode);
system("...your command...");
SetConsoleMode(ConsoleWin, mode);
By the way, your program may have the same problem even without executing any system(). It relies on default console settings, which in turn depend on system settings and user preferences. I suggest you to add this code at the beginning of your program:
DWORD mode;
GetConsoleMode(ConsoleWin, &mode);
mode |= ENABLE_WINDOW_INPUT | ENABLE_MOUSE_INPUT | ENABLE_EXTENDED_FLAGS;
SetConsoleMode(ConsoleWin, mode);