Problems with loops

[Mingzhi]

can anyone tell me what is wrong with my code?

#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
void input();
void compute();
void print();
char name[6][21];
float previous_balance [6];
float payments [6];
float charges [6];
void main()
{
input();
}

void input()
{
for (int counter=0; counter<6; counter++)
{
cout<<"Enter the last name for the "<<counter+1<<" customer."<<endl;
cin>>name[counter];
cout<<"Enter the previous balance for customer "<<name[counter]<<endl;
cin>>previous_balance [counter];
if (isdigit(previous_balance[counter])==0)
{
cout<<"Cannot contain letters."<<endl;
counter--;
}

}
}

sorry that the code looks abit messy. What I do not understand is, why it give me this when I typed a letter for cin>>previous_balance

Enter the last name for the ... customer
.
.
.
.
.
it will just flood the screen and keep repeating the same sentence above. I know that previous balance is a float, but i am just checking it to make sure it is really entered as a float. I have tried putting cin.get(): before every cin. However, it still give me the same problem.

[codegirl]

I'm not sure why it keeps repeating that sentence, but I can tell you one error in the code: you declared previous_balance to be of type float. That means it cannot hold letters. When you type a letter in the input and it tries to store the letter in previous_balance in the line:

cin>>previous_balance [counter];

that will create an error! If you want the user to be able to enter letters without the program crashing, you'll need to store the input in a string or char[] first, then check to see if it's a number before converting it to a float.

I don't know if that will fix your problem or not, but it should help!

[Speedy5]

a) Use code tags. On the top of each board here, there is a sticky on how to use them. Makes your code look nicer when you post it.

b) Do NOT use void main(). Use int main() and return 0. Why? Read the FAQ.

c) You're not supposed to put in letters when its expecting a number. It will screw things up.

[Cat]

Originally posted by Mingzhi
What I do not understand is, why it give me this when I typed a letter for cin>>previous_balance

Enter the last name for the ... customer
.
.
.
.
.
it will just flood the screen and keep repeating the same sentence above. I know that previous balance is a float, but i am just checking it to make sure it is really entered as a float. I have tried putting cin.get(): before every cin. However, it still give me the same problem.

If you try to read an invalid input (e.g. a letter when expecting a number) the stream goes into an error state; the number you get back is undefined. You need to check for the error state and recover from it before you can do anything else.

Once a stream errors, until the error is cleared, you can't read ANYTHING from it.

[Mingzhi]

Thank you so much for replying back to my queries. However, I am still a newbie lor & do not know how to convert data in a char to a floating point number. Need to learn more. Anyway, thanks for answering my queries