Thread: [Dev-C++] input validation

I'm having something strange occur.  When someone enters a negative 
number in my program for either the deposit amount or the withdrawal 
amounts, it loops and prompts for the user again...but it also subtracts 
the negative number from my running total!  Shouldn't the input 
validation keep that from happening?  Am I missing something?  The code 
is below with the suspected portions highlighted ...thanks!

int main()
{
//declare and initialize variables
float startBalance = 0;
float withdrawAmount = 0;
float depositAmount = 0;
float totalDeposits = 0;
float totalWithdrawals = 0;
float finalBalance = 0;
float runningBalance = 0;


//intro
cout<<endl;
cout<<"Welcome to the savings account balance calculator!!!"<<endl;
cout<<endl;


//prompt user for starting balance
cout<<"Please enter the starting balance in the savings account: ";
cin>>startBalance;
cout<<endl;

//add startBalance to runningBalance
runningBalance += startBalance;

//loop thru 3 month period
for(int i=1; i<=3; ++i)
{//begin month loop

*//prompt user for deposit amount
do
{//begin do while
cout<<"Please enter month "<<i<<" deposit amount: ";
cin>>depositAmount;
runningBalance += depositAmount;
totalDeposits += depositAmount;
//input validation
if (depositAmount < 0)
cout<<"Please enter a positive number."<<endl;
cout<<endl;
}//end do while
while (depositAmount < 0);*

*do
{//begin do while
//prompt user for withdrawal amount
cout<<"Please enter month "<<i<<" withdrawal amount: ";
cin>>withdrawAmount;
totalWithdrawals += withdrawAmount;
cout<<endl;
//input validation
if (withdrawAmount < 0 || withdrawAmount > runningBalance)
{cout<<"Please enter either a positive number or a number that isn't 
greater";
cout<<" then the balance."<<endl;
cout<<endl;}
}//end do while
while (withdrawAmount < 0 || withdrawAmount > runningBalance);
cout<<totalWithdrawals;
}//end month loop*


//calculate the final balance
finalBalance = runningBalance - totalWithdrawals;
cout<<endl;

//display output
cout<<fixed<<showpoint;
cout <<"Starting balance:\t$"<<setprecision(2)<<startBalance<<".\n\n";
cout <<"Total Deposits:\t\t$"<<setprecision(2)<<totalDeposits<<".\n\n";
cout <<"Total Withdrawals:\t$"<<setprecision(2)<<totalWithdrawals<<".\n\n";
cout <<"Final Balance:\t\t$"<<setprecision(2)<<finalBalance<<".\n";

  return 0;
}

The problem is solved...I was adding the totals before the input validation.

thx

You are joking, aren't you?

You perform:
runningBalance += depositAmount;
totalDeposits += depositAmount;

_before_ your input validation of the deposit amount.

You perform:

totalWithdrawals += withdrawAmount;

_before your input validation of the withdrawals amount.

Then _why_ are surprised that the values gets changed even for negative
inputs.  Why wouldn't they? How long did you spend looking for this error,
before settling for Internet Personal Guidance?

By the way: What's wrong with standard text mails? Are they too easy to
read, or do they consume too little bandwidth?

It is way better to try and find a way to post your source code using a
method that keeps the indentation (you do indent your code?), than in a
way where you can mark some source lines in bold. If you feel you need to
mark a spot, it is enough with a "<=== Problem here" note in the text.

/pwm

On Fri, 14 Mar 2008, Shawn wrote:

> I'm having something strange occur.  When someone enters a negative
> number in my program for either the deposit amount or the withdrawal
> amounts, it loops and prompts for the user again...but it also subtracts
> the negative number from my running total!  Shouldn't the input
> validation keep that from happening?  Am I missing something?  The code
> is below with the suspected portions highlighted ...thanks!