Thread: I can't figure this out!

I have this whole program working except for the following:

If the current balance goes to zero, then no more withdrawals should be made and it should output a message " Sorry you have no money to withdraw"

This is the only part I can't figure out how to do. I have been trying for days now. Can someone help? Code is below

Code:

#include <stdio.h>

int main ()

{
	 /*Variable Declarations*/
	 /*---------------------*/

	 int   x, withdrawals, deposits;
	 float deposit[50], withdrawal[50];
	 float total=0, balance;


	 /*Declare and initalize accumulators for closing balance*/
	 /*------------------------------------------------------*/

	 float sum= 0, count=0;

	 /*Display opening greeting to user*/
	 /*--------------------------------*/

	     printf ("\nWelcome to Colleen's Banking System\n\n");

	 /*Prompt user to input current balance in dollars and cents*/
	 /*---------------------------------------------------------*/

	  do
	  {
		  printf ("Enter current balance in dollars and cents: "  );
		  scanf  ("%f", &balance);
		  fflush (stdin);						//clear input screen

		  if (balance < 0 )
		  printf ("Beginning balance must be at least zero, please re-enter!\n\n");
	 } while (balance < 0 );            //end do loop

	 /*Prompt user to input number of withdrawals*/
	 /*------------------------------------------*/

		do
		{
		  printf ("\nEnter the number of withdrawals: " );
		  scanf  ("%d", &withdrawals);
		  fflush (stdin);                 //clear input screen

		  if (withdrawals < 0 )
		  printf ("Error: Number of withdrawals must be at least zero, please re-enter! \n");
	 } while (withdrawals < 0 );         //end do loop

	 /*Prompt user to input the number of deposits*/
	 /*-------------------------------------------*/

		do
		{
		  printf ("\nEnter the number of deposits: " );
		  scanf  ("%d", &deposits);
		  fflush (stdin);                 //clear input screen

		  if (deposits < 0 )
		  printf ("Error: Number of deposits must be at least zero, please re-enter! \n");
	 } while (deposits < 0 );            //end do loop

	 /*Promt user to input each deposit amount*/
	 /*---------------------------------------*/

	 for( x = 1; x <= deposits; x++)
	 {
		  printf ("Enter the amount of deposit #%i: ", x);
		  scanf  ("%f", &deposit[x]);
		  fflush (stdin);                  //clear input screen

	 /*Output appropriate message if deposit amount is less than zero.*/
	 /*---------------------------------------------------------------*/

	 if ( deposit < 0 )
		{
		  printf ("***Invalid entry. Deposit amount must be positive.***\n");
		  deposit[x] = deposit - deposit;
		  x--;
		}

		count = count + deposit[x];

	 } // end for loop

	 /*Prompt user to input each withdrawal amount*/
	 /*----------------------------------------------------*/

	 for( x = 1; x <= withdrawals; x++)
		{
		  printf ("Enter the amount of withdrawal #%i: ", x);
		  scanf  ("%f", &withdrawal[x]);
        fflush (stdin);                  //clear input screen

	 /*Output appropriate message if withdrawal amount is not positive.*/
	 /*----------------------------------------------------------------*/

	 if ( withdrawal < 0 )
		{
		  printf ("***Withdrawal amount must be positive.***\n");
		  withdrawal[x] = withdrawal - withdrawal;
		  x--;
		}

		/*Output appropriate message if withdrawal exceeds current balance.*/
		/*-----------------------------------------------------------------*/

	 if (withdrawal[x] > balance + deposit[x])
		{
		  printf ("***Withdrawal amount exceeds current balance. Please re-enter!***\n");
		  withdrawal[x] = withdrawal - withdrawal;
		  x--;
		}

	 sum = sum + withdrawal[x];

	  /*If balance goes to zero, no more withdrawals should be made*/
	  /*-----------------------------------------------------------*/

	 if (withdrawal[x] = balance + deposit[x])
	{
		  printf ("***Sorry you have no money to withdraw!***\n");
		  withdrawal[x] = withdrawal - withdrawal;
	}

	 } // end for loop

	 /*Output closing balance amount to user*/
	 /*-------------------------------------*/

	 total = (float) balance + count - sum;
	 printf ("\n***The closing balance is $%.2f***\n", total);

	 /*Display short advice for user based upon closing balance*/
	 /*--------------------------------------------------------*/

	 if (total >= 500000.00 )
		  printf ("***Time to invest some money!*** \n");
	 else
	 if (total > 15000.00&&total <49999.99 )
		  printf ("***Maybe you should consider a CD.*** \n");
	 else
	 if (total > 1000.00&&total <14999.99 )
		  printf ("***Keep up the good work.*** \n");
	 else
	 if (total >=0.00&&total< 999.99 )
		  printf ("***Your balance is getting low.***\n");

	 /*Output a Bank Record for user*/
	 /*-----------------------------*/

		  printf ("\n***Bank Record***");
		  printf ("\nStarting Balance: $ %.2f\n\n", balance);

	 for (x=1; x <= deposits; x++)
	 {
		  printf ("Deposit #%i:        %.2f\n", x, deposit[x]);
	 } //end for loop

	 for (x=1;  x <= withdrawals; x++)
	 {
		  printf ("\nWithdrawal #%i:     %.2f", x, withdrawal[x]);
	 } //end for loop

		  printf ("\n\nEnding Balance: $   %.2f\n", total);


} //end main

I want it that if the withdrawal amount exceeds the current balance (including new deposits) it should output the following " Withdrawal amount exceeds current balance, it should then reprompt the user for a lower withdrawal amount (which it does this)

and also That if the current balance goes to zero, no more withdrawals should be made and a appropriate message should display. (this is the part I am having problems with)

Another small question and I don't even know if this is possible. Is their any way to get the decimal points on the bank record to line up. I been trying to but haven't been sucessful.



I have updated the code in my first post.

Comparing the two floats:

Code:

if (withdrawal[x] = balance + deposit[x])

you should probably use the comparison ==, not the assignment =.

Also, comparing floats for exact equality is rarely going to work because floats are not exact. 23.50 could in fact be 23.500001 or 23.4999997. Even though they are close, they are not equal. Your best bet is to use => or =<

I actually updated it to this before even seeing your post, after reading more in the four books I have. Trying to self teach myself.
you should probably use the comparison ==, not the assignment =.

Confused on this part below. What am I changing in the program for this?

Also, comparing floats for exact equality is rarely going to work because floats are not exact. 23.50 could in fact be 23.500001 or 23.4999997. Even though they are close, they are not equal. Your best bet is to use => or =<

Code:

fflush(stdin);

Read this. There are usually numerous posts about this on the board... I'd suggest a quick search.

As for the comparison, for the purposes of dealing with this problem, many banks I believe always store data as cents and not dollars. Therefore all computations done on cents don't have to worry about round off problems or inaccuracies with floating point formats. If you are commited to using floats, then comparing such a float to another value using == might not work depending on the particular values involved. One way to deal with this is to use >= and <= to say whether or not the value you are checking is within a certain range of the value you are checking against. There is usually a defined constant in a header somewhere (<float.h> perhaps?) called FLT_EPSILON that represents the smallest possible float value (there is a cooresponding value called DBL_EPSILON for doubles). You can use this defined constant in the <= >= checks:

Code:

float value;
printf("Enter a value: ");
scanf("%f",&value);
// Test if entered value is equal to 23.5... beware of using == directly
if( value <= 23.5f + FLT_EPSILON && value >= 23.5f - FLT_EPSILON )
{
    // It is "equal"/"close enough"
}