Thread: Flushing the input buffer.

Well, when my program runs the block of code below, I enter help for the input, and it does the correct thing, but when system("PAUSE"); comes up and I hit a key, the console window flashes, and wont do anything. I ultimately have to shut it down with the X at the top right-hand corner, which locks up my CPU. DA has told me that I need to flush the input buffer, so I used fflush(stdin); which was the only thing I know. What am I doing wrong?

Code:

/* this is the code that I think is the culprit*/
clearscreen
_header
br
int cmndline;
cout<<"INPUT: ";
cin>>cmndline;
if(strcmp("string help", "string help") ==0)
{
fflush(stdin);
cout<<"hello";
br
pause
goto startofprog;
}

br, _header, clearscreen, and pause are all macros.

Pause is a macro for system("PAUSE");


if you want to compile this for yourslf, use the following block of code:

Code:

#include <iostream.h>
#include <stdlib.h>
#include <windows.h>
#include <string.h>

int main()
{
startofprog:int cmndline;
cout<<"INPUT: ";
cin>>cmndline;
if(strcmp("string help", "string help") ==0)
{
fflush(stdin);
cout<<"hello";
cout<<endl;
system("PAUSE");
goto startofprog;
}
return 0;
}

Thanks in advance for any help!

i think this may work for your needs,

// where INT_MAX s the maximum number of characters to clear up to '\n'

cin.ignore( INT_MAX, '\n' );

I'm pretty sure this is what you're trying to accomplish(please dont yell at me for using int..it works!)
//edit yeah sorry i meant goto..but hey, i'm just manipulating his old post so it functions right

Code:

#include <iostream.h>
#include <stdlib.h>
#include <windows.h>
#include <string.h>
int main()
{
	startofprog:
	char cmndline[20];
	cout<<"INPUT: ";
	cin>>cmndline;
	if(strcmp(cmndline, "help") ==0)
	{
		cout<<"hello";
		cout<<endl;
	}
	if(strcmp(cmndline, "exit")!=0)
	goto startofprog;
	return 0;
}

I'm pretty sure this is what you're trying to accomplish(please dont yell at me for using int..it works!)

Using int? No, that's not what I'd start yelling about...

goto startofprog;

Now that on the other hand...

Quzah.

Civix,

Please, don't use 'fflush(stdin);'. Prelude will tear her hair out (provided she hasn't already done so) if she sees this again in anyone's post.

The behavior - from what I've gathered from the gazillion threads that have been posted concerning this recently - is undefined. Not good. (That much, I do know! )

no-one suggests using cin.ignore() which is an excellent choice, and the superior one to fflush(stdin).

Also, do away with the 'goto' command. It's legitimate, but not a good habit to form, hence, quzah's post.

Personal note:

if you want to compile this for yourslf, use the following block of code:

First, it won't compile because you don't include the appropriate, terminating brace from the IF statement. Without it, we have no idea what your logic is, i.e. which statements you want included inside of the IF statement.

Second, 'goto' will never allow 'return 0;' to execute. One step beyond an infinite loop. You now have an infinite program. (I refer you back to quzah's post.)

I leave the conclusion of this to you. [hint] You've given us supplemental code that's more problematic than what the original was. [/hint]

-Skipper

Whoops, dumb, common Civix mistake. Sorry

EDIT: Fixed the first post!

Civix,

Whoops, dumb, common Civix mistake. Sorry

I doubt that.

-Skipper