problem with _kbhit and i/o exception handling

[vikas]

hi,
I want to generate random numbers in c++ (using vc++ 6.0) on hit of
enter. I am using _kbhit(), but don't know how to reset it, so that I
can use it again, can anybody help me with this.
code is say like following.
#include <iostream>
#include <conio.h>
#include <windows.h>
using namespace::std;
int main(int argc, char* argv[])
{
for(int i=0; i<10; i++)
{
cout << "hit enter to generate random number" << endl;
int ran1 = func1();
cout << "hit enter to generate random number" << endl;
int ran2 = func2();
}

return 0;
}
int func1()
{
int ret;

while(!_kbhit())
{
ret = rand()%10;
Sleep(10);
}
return ret;
}
int func2()
{
int ret;

while(!_kbhit())
{
ret = rand()%20;
Sleep(10);
}
return ret;
}

There is another problem with I/O exception handling:
i tried to read an int correctly using following code. but in case of
exception it is caught but cin doesn't execute inspite of clearing it:

int main(int argc, char* argv[])
{
int i;
bool check = false;

cin.exceptions(ios_base::failbit);

while(!check)
{
try{
cout << "enter a number: ";
cin >> i;
check = true;
}catch(ios_base::failure){
cin.clear();
}

}

return 0;
}

Thanks,
vikas

[mlimber]

vikas wrote:

hi,
I want to generate random numbers in c++ (using vc++ 6.0) on hit of
enter. I am using _kbhit(), but don't know how to reset it, so that I
can use it again, can anybody help me with this.
code is say like following.
#include <iostream>
#include <conio.h>
#include <windows.h>
using namespace::std;
int main(int argc, char* argv[])
{
for(int i=0; i<10; i++)
{
cout << "hit enter to generate random number" << endl;
int ran1 = func1();
cout << "hit enter to generate random number" << endl;
int ran2 = func2();
}

return 0;
}
int func1()
{
int ret;

while(!_kbhit())
{
ret = rand()%10;
Sleep(10);
}
return ret;
}
int func2()
{
int ret;

while(!_kbhit())
{
ret = rand()%20;
Sleep(10);
}
return ret;
}
_kbhit is a non-standard Microsoft extension. You'll want to ask this
question in a Microsoft newsgroup (e.g.
comp.os.ms-windows.programmer.win32).

There is another problem with I/O exception handling:
i tried to read an int correctly using following code. but in case of
exception it is caught but cin doesn't execute inspite of clearing it:

int main(int argc, char* argv[])
{
int i;
bool check = false;

cin.exceptions(ios_base::failbit);

while(!check)
{
try{
cout << "enter a number: ";
cin >> i;
check = true;
}catch(ios_base::failure){
cin.clear();
}

}

return 0;
}

What do you mean by "doesn't execute"? Why does the input fail? I'm
guessing that you typed an invalid number (say, "xyz"), and clearing
the state doesn't clear the underlying buffer (or something to that
effect). Try adding this after the cin.clear():

cin.seekg( 0, ios::end );

Cheers! --M

[vikas]

you are right, problem is due to abnormal condition of underlying
buffer. I didn't knew how to do that.
I checked with
cin.seekg( 0, ios::end );

it does solve the problem

thanks M,

mlimber wrote:

vikas wrote:

hi,
I want to generate random numbers in c++ (using vc++ 6.0) on hit of
enter. I am using _kbhit(), but don't know how to reset it, so that I
can use it again, can anybody help me with this.
code is say like following.
#include <iostream>
#include <conio.h>
#include <windows.h>
using namespace::std;
int main(int argc, char* argv[])
{
for(int i=0; i<10; i++)
{
cout << "hit enter to generate random number" << endl;
int ran1 = func1();
cout << "hit enter to generate random number" << endl;
int ran2 = func2();
}

return 0;
}
int func1()
{
int ret;

while(!_kbhit())
{
ret = rand()%10;
Sleep(10);
}
return ret;
}
int func2()
{
int ret;

while(!_kbhit())
{
ret = rand()%20;
Sleep(10);
}
return ret;
}

_kbhit is a non-standard Microsoft extension. You'll want to ask this
question in a Microsoft newsgroup (e.g.
comp.os.ms-windows.programmer.win32).

There is another problem with I/O exception handling:
i tried to read an int correctly using following code. but in case of
exception it is caught but cin doesn't execute inspite of clearing it:

int main(int argc, char* argv[])
{
int i;
bool check = false;

cin.exceptions(ios_base::failbit);

while(!check)
{
try{
cout << "enter a number: ";
cin >> i;
check = true;
}catch(ios_base::failure){
cin.clear();
}

}

return 0;
}

What do you mean by "doesn't execute"? Why does the input fail? I'm
guessing that you typed an invalid number (say, "xyz"), and clearing
the state doesn't clear the underlying buffer (or something to that
effect). Try adding this after the cin.clear():

cin.seekg( 0, ios::end );

Cheers! --M