Programming Forums > Application Development > C

jch02140 · Jul 30th, 2005, 4:36 PM

Hi,

I am trying to print out a number entered by user that is positive and multiples of 10... But when I compile and execute the code below, only negative numbers will loop but any positive numbers will print out... Where have I done wrong?....

(Toggle Plain Text)

int main(int argc, char *argv[])
{
  int x;
  printf("Welcome to Carleton Bank.\n");
  printf("Please enter an amount...\n");
  scanf("%d",&x);
 
  while((x < 0) && (x % 10 != 0))
  {
        printf("Illegal number. Try again.\n");
        scanf("%d",&x);
  }
             
  printf("%d",x);
 
  return 0;
}

EverLearning · Jul 30th, 2005, 4:46 PM

(Toggle Plain Text)

  while((x < 0) || (x % 10 != 0))
  {
        printf("Illegal number. Try again.\n");
        scanf("%d",&x);
  }

I think that should fix it.
If you use && in this case, while() is not going to execute unless both coniditons are True.

EDIT: @7LSqr: saw that too

Ancient Dragon · Jul 30th, 2005, 4:51 PM

in addition to what the others said, your loop is an infinite loop -- if it executes the first time it will just sit there an execute forever because x is never changed.

stevengs · Jul 30th, 2005, 5:05 PM

Quote:

Originally Posted by Ancient Dragon

in addition to what the others said, your loop is an infinite loop -- if it executes the first time it will just sit there an execute forever because x is never changed.

scanf won't change x? I must be missing something...

OpenLoop · Jul 30th, 2005, 5:22 PM

Quote:

Originally Posted by stevengs

scanf won't change x? I must be missing something...

Dragon must've missed that line, yes scanf will change x

L7Sqr · Jul 30th, 2005, 4:47 PM

Quote:

(x < 0) && (x % 10 != 0)

I believe what you are looking for is:

(Toggle Plain Text)

(x < 0) || (x % 10 != 0)

That way if either of the conditions is true the loop continues; not only if they both are true...

[edit]oops...Sorry Everlearning...

[/edit]

jch02140 · Jul 30th, 2005, 5:05 PM

It works now after I change the AND to OR operator. Thank for pointing that out.

Jul 30th, 2005, 4:36 PM	#1
jch02140 Newbie Join Date: Jul 2005 Posts: 15 Rep Power: 0	Problem with while loop... Hi, I am trying to print out a number entered by user that is positive and multiples of 10... But when I compile and execute the code below, only negative numbers will loop but any positive numbers will print out... Where have I done wrong?.... (Toggle Plain Text) int main(int argc, char argv[]) { int x; printf("Welcome to Carleton Bank.\n"); printf("Please enter an amount...\n"); scanf("%d",&x); while((x < 0) && (x % 10 != 0)) { printf("Illegal number. Try again.\n"); scanf("%d",&x); } printf("%d",x); return 0; } int main(int argc, char argv[]) { int x; printf("Welcome to Carleton Bank.\n"); printf("Please enter an amount...\n"); scanf("%d",&x); while((x < 0) && (x % 10 != 0)) { printf("Illegal number. Try again.\n"); scanf("%d",&x); } printf("%d",x); return 0; }

Jul 30th, 2005, 4:46 PM	#2
EverLearning Hobbyist Programmer Join Date: May 2005 Location: Indiana Posts: 130 Rep Power: 4	(Toggle Plain Text) while((x < 0) \|\| (x % 10 != 0)) { printf("Illegal number. Try again.\n"); scanf("%d",&x); } while((x < 0) \|\| (x % 10 != 0)) { printf("Illegal number. Try again.\n"); scanf("%d",&x); } I think that should fix it. If you use && in this case, while() is not going to execute unless both coniditons are True. EDIT: @7LSqr: saw that too __________________ got math? yumm... "All men by nature desire to know" -Aristotle, Metaphysics

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Jul 30th, 2005, 4:51 PM	#3
Ancient Dragon PFO God In Training Join Date: Jun 2005 Location: near St Louis, MO. (USA) Posts: 600 Rep Power: 4	in addition to what the others said, your loop is an infinite loop -- if it executes the first time it will just sit there an execute forever because x is never changed.

Jul 30th, 2005, 5:05 PM	#7
jch02140 Newbie Join Date: Jul 2005 Posts: 15 Rep Power: 0	It works now after I change the AND to OR operator. Thank for pointing that out.

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Programming Forums > Application Development > C

Problem with while loop...