beep sound till any input

问题

I am making a Quiz program. So what I want is whenever any question in presented before the user, then he has 30 seconds to answer it. And in these 30 seconds I want the beep sound ('\a') at an interval of 1 second. Now I want is that this beep sound should stop as soon as the user enters any input. I have created this small function to produce the beep sound for 30 sec void beep(){ for(int i=0;i<30;i++){cout<<"\a"; Sleep(1000); } } But I don't know how to stop it as soon as the user enters his/her answer because once I call it nothing can be done until its over. Can anyone give any workaround for it?

回答1:

Disclaimer: I'm not a Windows programmer, I don't know if this is good style or even if it will compile or work. I can't test it here. However, as no one else has given a solution, it's a starting point. I'll edit this answer as I learn more, and hopefully someone who knows more about this will turn up.

Edit: I faked out _kbhit() to a trivial function returning false, and it at least compiles and looks like it runs ok

Edit: Ok I do have ms visual studio at work, I just never use it. The code as it is right now compiles and works (I suspect the timing is off though).

Edit: Updated it to immediately read back the key that was hit (rather than waiting for the user to hit enter).

This is the important function: http://msdn.microsoft.com/en-us/library/58w7c94c%28v=vs.80%29.aspx

#include <windows.h>
#include <conio.h>
#include <ctime>
#include <iostream>
#include <string>

int main()
{
    time_t startTime, lastBeep, curTime;
    time(&startTime);
    lastBeep = curTime = startTime;
    char input = '\0';

    while ( difftime(curTime,startTime) < 30.0 )
    {
        if ( _kbhit() ) // If there is input, get it and stop.
        {
            input = _getch();
            break;
        }
        time(&curTime);
        if ( difftime(curTime,lastBeep) > 1.0 ) // More than a second since last beep?
        {
            std::cout << "\a" << "second\n" << std::flush;
            lastBeep = curTime; // Set last beep to now.
        }
    }
    if ( input )
    {
        std::cout << "You hit: \"" << input << "\"\n" << std::flush;
    }

    return 0;
}

回答2:

You need to do a loop which maintains the "beginning time" somewhere, beeps every time 1 sec has gone and keeps checking if there is valid input. and exits if 30secs have gone or valid input is given. (or wrong input)

pseudo:

start=now();
lastbeep=start;
end=start+30secs
noanswer=true
while(now()<end&&noanswer)
{
   sleep(100ms)
   noanswre=checkforanswerwithoutblocking();
   if(now()-lastbeep>1sec)
   {
      beepOnce();lastbeep+=1sec;
   }
}
checkIfAnswerIsCorrect();
doStuff();

回答3:

something rough i can suggest is

void beep(){ 
 char press='n';
for(int i=0;i<30;i++)
   for(int j=0;j<100;j++) 
    {     if(press=='y')
                 return;
           cout<<"\a";
            sleep(10);
     }

回答4:

For windows: #include <windows.h> ... Beep(1480,200); // for example. ...

Beep() executes in separate thread in kernel (as i know), so you can do not care about multithreading - while it executes, your profram can check the input, or type new question, for example

来源：https://stackoverflow.com/questions/11778115/beep-sound-till-any-input

标签

c++

audio

beep