need help with a loop

Darkw1sh · 09-12-2009, 08:21 PM

I have a program,
and i need to create a loop....

I want a do you want to continue loop I have been having so much trouble with it i have tried many things and its not working for example

#define FALSE 0
#define TRUE 1
........................
loop=FALSE

while (loop == FALSE)
{
/*STATEMENTS!!!!*/

printf (" Would you like to try again , please enter y/n")
scanf ("%c", loop)
if ((loop ==y) || (loop==Y))
loop=FALSE
else if ((loop ==n) || (loop==N))
loop=TRUE

TY TY maybe have error checking or another loop for that section so if any1 enters G or w.e

tabstop · 09-12-2009, 08:41 PM

I assume you used 'y' and 'Y' etc. You should also look into [code] and [/code] in the sticky at the top of the forum.

Darkw1sh · 09-12-2009, 08:47 PM

that didnt help at all!

Dino · 09-12-2009, 08:50 PM

A WHILE loop written this way will never be entered:

Code:

while (loop == FALSE)

tabstop · 09-12-2009, 08:56 PM

Quote:

Originally Posted by Darkw1sh

that didnt help at all!

Well, maybe next time you should ask a question. Since the loop you posted works (assuming you use real character constants), it's hard to guess what you think the error is. (EDIT: If you weren't careful with your input in the part you didn't post, you might have to use " %c" (notice carefully the difference) in your scanf statement.)

Quote:

Originally Posted by Dino

A WHILE loop written this way will never be entered:

Code:

while (loop == FALSE)

What?

Adak · 09-12-2009, 08:58 PM

Something like this?

Code:

char loop;

loop = 'y';

while (loop == 'y' || loop == 'Y')
{
   /*STATEMENTS!!!!*/

   printf (" Would you like to try again , please enter y/n")
   scanf ("%c", &loop)    //you forgot the ampersand which scanf() needs
   
}

You're Rube Goldberg of the loop was confusing the issue. KISS.

If the variable loop is going to control the while statement, and you want it to be either 'y' or 'n' (or 'Y' or 'N'), then you don't need TRUE or FALSE, at all.

Hope that makes sense.

Dino · 09-12-2009, 09:04 PM

Quote:

Originally Posted by tabstop

Well, maybe next time you should ask a question. Since the loop you posted works (assuming you use real character constants), it's hard to guess what you think the error is. (EDIT: If you weren't careful with your input in the part you didn't post, you might have to use " %c" (notice carefully the difference) in your scanf statement.)

What?

Oops - duh. Sorry about that. Too much wine with dinner.

Darkw1sh · 09-12-2009, 09:18 PM

TY TY trying it now!

Quote:

Originally Posted by Adak

Something like this?

Code:

char loop;

loop = 'y';

while (loop == 'y' || loop == 'Y')
{
   /*STATEMENTS!!!!*/

   printf (" Would you like to try again , please enter y/n")
   scanf ("%c", &loop)    //you forgot the ampersand which scanf() needs
   
}

You're Rube Goldberg of the loop was confusing the issue. KISS.

If the variable loop is going to control the while statement, and you want it to be either 'y' or 'n' (or 'Y' or 'N'), then you don't need TRUE or FALSE, at all.

Hope that makes sense.

quzah · 09-12-2009, 09:19 PM

Let me answer your next question: It's looping twice, because you're using scanf, and you should be using something better. See the FAQ about reading input from a user.

Quzah.

Darkw1sh · 09-12-2009, 09:20 PM

Code:

/*Included Files*/
#include <stdio.h>
#include <math.h>

int main(void)
{

float side1, side2, side3, s, area;
char loop, y,Y, n,N, ch;

while (loop == 'y' || loop == 'Y')
{



  /*Input*/
    printf  ("Enter the value for side 1:" );
    scanf ("%f", &side1);
    printf  ("Enter the value for side 2:" );
    scanf ("%f", &side2);
          printf  ("Enter the value for side 3:" );
    scanf ("%f, %c", &side3);
	ch=getchar();
          /*Error Checking*/
     if (side1&&side2&&side3 !=0)
     {
			if ((side1+side2<=side3) || (side1+side3<=side2) || (side2+side3<=side1))
			printf ( "The triangle is invalid.\n");
			else if ((side1==side2) && (side2==side3))
			{
				printf ( "The triangle is an equilateral triangle.\n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
			else if ((side1==side2) || (side1==side3) || (side2==side3))
			{
				printf ( "The triangle is isosceles.\n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
			else if ((side1!=side2) && (side2!=side3) && (side1!=side3))
			{
				printf ( "The triangle is scalene. \n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
   		}
	 else printf ( "The triangle is invalid.\n");
   printf ( "Would you like to try another triangle? Enter Y/N:");
	scanf ("%c", &loop);

} 
return 0;
}

this is what i got and for some reason the loop does not work at all it doesn't let me even run the program

tabstop · 09-12-2009, 09:22 PM

Well, yes. The loop only happens if loop is 'Y' or 'y'. Since loop is 'bob' that isn't true. You may want to initialize your variables.

Darkw1sh · 09-12-2009, 09:48 PM

hrm its not working... no matter what i have done i am new to C/C++ and this loop wont work

rags_to_riches · 09-12-2009, 10:56 PM

Listen...see this?

Code:

char loop, y,Y, n,N, ch;

while (loop == 'y' || loop == 'Y')

You never initialize the variable loop to a value. Therefore, it could contain ANY value. The chances of that value being 'Y' or 'y' are probably pretty slim, so you won't enter the loop.

Do you get it?

Adak · 09-13-2009, 05:01 AM

You don't need the y,Y,n or N variables, but I left them in so you could polish it up.

This is working code.

Code:

/*Included Files*/
#include <stdio.h>
#include <math.h>

int main(void)
{

  float side1, side2, side3, s, area;
  char loop, y,Y, n,N, ch;

  //with while loops you frequently need to "prime the pump" (assign the
  //value of your control variable).
  loop = 'y';   
  while (loop == 'y' || loop == 'Y')
  {
    /*Input*/
    printf  ("Enter the value for side 1:" );
    scanf ("%f", &side1);
    
    printf  ("Enter the value for side 2:" );
    scanf ("%f", &side2);
    
    printf  ("Enter the value for side 3:" );
    scanf ("%f, %c", &side3);
    
    /*Error Checking*/
    if (side1&&side2&&side3 !=0)
    {
			if ((side1+side2<=side3) || (side1+side3<=side2) || (side2+side3<=side1))
			  printf ( "The triangle is invalid.\n");
			else if ((side1==side2) && (side2==side3))
			{
				printf ( "The triangle is an equilateral triangle.\n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
			else if ((side1==side2) || (side1==side3) || (side2==side3))
			{
				printf ( "The triangle is isosceles.\n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
			else if ((side1!=side2) && (side2!=side3) && (side1!=side3))
			{
				printf ( "The triangle is scalene. \n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
    }
	  else printf ( "The triangle is invalid.\n");

    printf ( "Would you like to try another triangle? Enter Y/N:");
    //ch = getchar();
    scanf (" %c", &loop);

  } 
  ch++;              //just stops a stupid warning on my compiler
  return 0;

}
/*
When you use scanf(), it may leave a newline char '\n', in the keyboard
buffer. A following scanf() for a number, will skip that '\n' char, and act
like you want.

A following scanf() for a char or a string, will not. It will see the '\n'
as the only char that you want to enter, and "skip" over the scan(), 
goofing up your program.

There are two common solutions:

1) Use a getchar() to "pull" the '\n' char, off the keyboard buffer, or
2) Put a space into the scanf() function, telling it to ignore the first
char it runs across. 

An example of #1: 
ch = getchar();
scanf ("%c", &loop);

An example of #2:
scanf (" %c", &loop); //note the space before the %c
*/

Darkw1sh · 09-13-2009, 09:00 PM

well thank you for everything i did a little research and got a lot done but now i have 1 last problem, if u run the following code when it asks yes or no to redo the code if i print yes it writes "would you like to redo....y/n?" and on the same line it prints "Please enter side 1:" how would i get rid of that repetition
heres the code if i can explain anything in anymore detail please let me know

Code:

/*Included Files*/
#include <stdio.h>
#include <math.h>
#define FALSE 0
#define TRUE 1

int main(void)
{

float side1, side2, side3, s, area;
char loop,  ch, restart;
loop= FALSE;


while (loop == FALSE)
{


	restart = 0;
  /*Input*/
    printf  ("Enter the value for side 1:" );
    scanf ("%f", &side1);
    printf  ("Enter the value for side 2:" );
    scanf ("%f", &side2);
          printf  ("Enter the value for side 3:" );
    scanf ("%f, %c", &side3);
	ch=getchar();
          /*Error Checking*/
     if (side1&&side2&&side3 !=0)
     {
			if ((side1+side2<=side3) || (side1+side3<=side2) || (side2+side3<=side1))
			printf ( "The triangle is invalid.\n");
			else if ((side1==side2) && (side2==side3))
			{
				printf ( "The triangle is an equilateral triangle.\n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
			else if ((side1==side2) || (side1==side3) || (side2==side3))
			{
				printf ( "The triangle is isosceles.\n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
			else if ((side1!=side2) && (side2!=side3) && (side1!=side3))
			{
				printf ( "The triangle is scalene. \n");
				s =(side1+side2+side3)/2;
				area=sqrt(s*(s-side1)*(s-side2)*(s-side3));
				printf ("The area of the triangle is %6.2f\n", area);
			}
   		}
	 else printf ( "The triangle is invalid.\n");
	
	do
	{
	
	printf ( "Would you like to try another triangle? Enter Y/N:");
	scanf ("%c, %c", &loop);
	
	if ((loop=='Y')||(loop=='y'))
	{
		loop=FALSE;
		restart = 1;
	}
	else if ((loop=='N') || (loop=='n'))
	{
		loop=TRUE;
		restart=1;
	}
	else restart = 0;
	}
	while (restart==0);
}

return 0;
}

09-12-2009, 08:21 PM	#1
Darkw1sh Registered User Join Date: Sep 2009 Posts: 10	need help with a loop I have a program, and i need to create a loop.... I want a do you want to continue loop I have been having so much trouble with it i have tried many things and its not working for example #define FALSE 0 #define TRUE 1 ........................ loop=FALSE while (loop == FALSE) { /STATEMENTS!!!!/ printf (" Would you like to try again , please enter y/n") scanf ("%c", loop) if ((loop ==y) \|\| (loop==Y)) loop=FALSE else if ((loop ==n) \|\| (loop==N)) loop=TRUE TY TY maybe have error checking or another loop for that section so if any1 enters G or w.e
Darkw1sh is offline

09-12-2009, 08:47 PM	#3
Darkw1sh Registered User Join Date: Sep 2009 Posts: 10	that didnt help at all!
Darkw1sh is offline

09-12-2009, 08:50 PM	#4
Dino Jack of many languages Join Date: Nov 2007 Location: Katy, Texas Posts: 2,070	A WHILE loop written this way will never be entered: Code: while (loop == FALSE) __________________ Mac and Windows cross platform programmer. Ruby lover.
Dino is offline

09-12-2009, 08:58 PM	#6
Adak Registered User Join Date: Sep 2006 Posts: 3,139	Something like this? Code: char loop; loop = 'y'; while (loop == 'y' \|\| loop == 'Y') { /STATEMENTS!!!!/ printf (" Would you like to try again , please enter y/n") scanf ("%c", &loop) //you forgot the ampersand which scanf() needs } You're Rube Goldberg of the loop was confusing the issue. KISS. If the variable loop is going to control the while statement, and you want it to be either 'y' or 'n' (or 'Y' or 'N'), then you don't need TRUE or FALSE, at all. Hope that makes sense.
Adak is offline

09-12-2009, 09:19 PM	#9
quzah +++ OK NO CARRIER Join Date: Oct 2001 Posts: 10,637	Let me answer your next question: It's looping twice, because you're using scanf, and you should be using something better. See the FAQ about reading input from a user. Quzah. __________________ Hundreds of thousands of dipshits can't be wrong. Are you up for the suck?
quzah is offline

09-12-2009, 08:41 PM	#2
tabstop and the Hat of Guessing Join Date: Nov 2007 Posts: 8,805	I assume you used 'y' and 'Y' etc. You should also look into [code] and [/code] in the sticky at the top of the forum.
tabstop is offline

09-12-2009, 09:22 PM	#11
tabstop and the Hat of Guessing Join Date: Nov 2007 Posts: 8,805	Well, yes. The loop only happens if loop is 'Y' or 'y'. Since loop is 'bob' that isn't true. You may want to initialize your variables.
tabstop is offline

09-12-2009, 09:48 PM	#12
Darkw1sh Registered User Join Date: Sep 2009 Posts: 10	hrm its not working... no matter what i have done i am new to C/C++ and this loop wont work
Darkw1sh is offline

09-12-2009, 10:56 PM	#13
rags_to_riches and the Hat of Ass Join Date: Dec 2007 Posts: 810	Listen...see this? Code: char loop, y,Y, n,N, ch; while (loop == 'y' \|\| loop == 'Y') You never initialize the variable loop to a value. Therefore, it could contain ANY value. The chances of that value being 'Y' or 'y' are probably pretty slim, so you won't enter the loop. Do you get it?
rags_to_riches is offline

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