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Jun 1st, 2004

how can i make the program depend on time

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hi , i am using simple console application and i am asking about the way to make the program depend on time insead of dependng on pressing keys for example, i want siplay the word "Hello.." and after 5 seconds it changes to "World" , to elaborate .. i want system("pause") but depending on time not on keys.
thnx

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dooda man

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since May 2004

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Jun 1st, 2004

Re: how can i make the program depend on time

Something like this?

C Syntax (Toggle Plain Text)
#include <stdio.h>
#include <time.h>
 
int main(void)
{
   time_t now, then = time(&now) + 5;
   if ( now != (time_t)(-1) )
   {
	  const char *text[] = {"Hello","World"};
	  size_t i = 0;
	  for ( ;; )
	  {
		 printf("\r%s", text[i]);
		 fflush(stdout);
		 if ( ++i >= sizeof text / sizeof *text )
		 {
			i = 0;
		 }
		 while ( then > time(&now) );
		 then = now + 5;
	  }
   }
   return 0;
}
#include <stdio.h>
#include <time.h>

int main(void)
{
   time_t now, then = time(&now) + 5;
   if ( now != (time_t)(-1) )
   {
	  const char *text[] = {"Hello","World"};
	  size_t i = 0;
	  for ( ;; )
	  {
		 printf("\r%s", text[i]);
		 fflush(stdout);
		 if ( ++i >= sizeof text / sizeof *text )
		 {
			i = 0;
		 }
		 while ( then > time(&now) );
		 then = now + 5;
	  }
   }
   return 0;
}

Dave Sinkula

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long time no c

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since Apr 2004

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Jun 4th, 2004

Re: how can i make the program depend on time

Hello,

Unfortunately, that code above is unfriendly to other processes on the computer, because of the infinite loop that is run. Granted, in this close example, you are looking at 5 seconds, and that won't cause something to croke.

But, if I had to do a delay in the minutes range, that would peg the CPU, and cause a system admin to come and shut you down. That might not matter today, but back in the day when CPU seconds = money on the mainframe, a loop like that could run you out of money.

There has to be a better way without doing the raw iteration!

(I had a program that needed the delay, and I ended up using a part C++ program and part of a BASH shell script so that I could do the wait() command that did not use CPU power during the delay)

Christian

kc0arf

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Posting Virtuoso

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since Mar 2004

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Jun 5th, 2004

Re: how can i make the program depend on time

You could use GetTickCount().

C Syntax (Toggle Plain Text)
double next_time  = GetTickCount();
 
while (true)
{
       if(GetTickCount() >=next_time + 100)
       {
             cout<<"Bong\n";
             next_time  = GetTickCount();
       }
}
double next_time  = GetTickCount();

while (true)
{
       if(GetTickCount() >=next_time + 100)
       {
             cout<<"Bong\n";
             next_time  = GetTickCount();
       }
}

FireNet

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