Same problem with a new aspect

iam3 · 11-06-2001, 03:51 AM

Note: I have asked a question about the same code before. But now it is a different question. I have just started to learn C++ ;-)

#include <iostream>
main( ) {
char command[40];
int time_of_day;
const bool ever = 1;
for ( ;ever; ) {
cin >> time_of_day >> command;
cout << "Command was " << command << " at time " << time_of_day << endl;
}
}

*^*****************************************
Input = 13 shoot if they shoot first
Output
******
Command was shoot at time 13
Command was at time 13
Command was at time 13
Command was at time 13........

Input = 12:00 fire
Output
******
Command was :00 at time 12
Command was at time 12
Command was at time 12....
*******************************************
Question
********
1: Why do I get infinite loops in both cases?
2: It prints "Command was at time 12 " after first time. Why it does not print " Command was :00 at time 12 "
as before.

isajera · 11-06-2001, 02:51 PM

well, the infinite loop part is easy... it's just because you have the

for( ;ever; ){

//stuff...

}

loop in there. unless there's a break in the loop, it's never going to stop. if you just want it to print once, then just comment out the loop.

crabboy · 11-07-2001, 12:23 AM

Your infinite loop is caused by your for condition. I'm sure you are expecting cin to prompt you for more input but your program shoots off into never never land. Your problem is bad data you are entering in. cin is interpreting the data you enter in the following way:

Data: 13 shoot if they shoot first

Loop1:
time_of_day = 13
command = shoot
Loop2:
time_of_day = if (error; all bets are off from here)
command = shoot
Loop3:
...

Your program works if you enter data like this:
data: 13 shoot 14 dude 15 kill 16 hello

If you want to enter a string after the number it is a bit tricker. You will have to use get or getline. I think they are cin members.

Here is a way to check for bad data:

Code:

#include <iostream>

main( )
{
   char command[40];
   int time_of_day;
   const bool ever = 1;
   do
   {
      cin >> time_of_day >> command;

      if ( cin.fail() )
         cout << "Get lost you idiot!" << endl;
      else
         cout << "Command was " << command 
                 << " at time " 
                 << time_of_day << endl
;

   } while ( !cin.fail() && !cin.eof() );
}