How to end a for loop with entry of particular value??

[tp09]

I have a for loop in which values are entered for two different arrays, using two cout statements.

I need a way to end the loop and continue with the rest of the function after the value "-1" is entered into the first array. -1 is a signal that all data has been read.

I tried to use if and then break, but that didn't work. What other ways are there to end the loop? thanks so much for any help!

I am very new to programming, as may be obvious.

Here is part of what I have so far:

  const int size = 100;
	int id[size], I;
	double balance[size];

	for (I=0; I<size; I++)
	{
			cout << "Enter the customer's ID number: ";
			cin >> id[I];
			
			while (id[I]<1000||id[I]>9999)
			{	cout << "You have entered an invalid ID.  Please  reenter: ";
				cin >> id[I];
			}

			cout << "Enter the customer's balance: ";
				cin >> balance [I];

			while (balance[I]>10000)
			{	cout << "You have entered an incorrect balance.  Please reenter: ";
				cin >> balance[I];
			}
	}

I would like to insert some sort of statement immediately after the first cout statement that would end the loop when id[I] == -1. I don't want it to go on to the while statements or the next cout one.

[AZlan LB]

Post what you have already written so that we can see where you are going wrong.

Alan

[ironic]

you could either use if/else:

	for (I=0; I<size; I++)
	{
			cout << "Enter the customer's ID number: ";
			cin >> id[I];
			if (cin != -1) {
			    while (id[I]<1000||id[I]>9999)
			    {	cout << "You have entered an invalid ID.  Please  reenter: ";
			    	cin >> id[I];
			    }

			    cout << "Enter the customer's balance: ";
			    	cin >> balance [I];

			    while (balance[I]>10000)
			    {	cout << "You have entered an incorrect balance.  Please reenter: ";
			    	cin >> balance[I];
			    }
                        }
	}

or as you said use break:

	for (I=0; I<size; I++)
	{
			cout << "Enter the customer's ID number: ";
			cin >> id[I];
			if (cin == -1) break;

			while (id[I]<1000||id[I]>9999)
			{	cout << "You have entered an invalid ID.  Please  reenter: ";
				cin >> id[I];
			}

			cout << "Enter the customer's balance: ";
				cin >> balance [I];

			while (balance[I]>10000)
			{	cout << "You have entered an incorrect balance.  Please reenter: ";
				cin >> balance[I];
			}
	}

note that the break method immediately stopps the loop while the upper example just proceeds with the next item. This is identically to use continue;


hope this helps


ironic

[chenwei86a]

ironic, in your first part of the program,

you forgot to write "else "

it should be like this:

if (cin != -1) 
{
    ...
}
else
{
    break;
}

[tp09]

thanks so much for your help, ironic and chenwei86a. I got it to work!

[Duthomhas]

I would avoid special entries like -1.
Also, (cin != -1) makes no sense...

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

// Handy little function to convert string to number
template <typename T>
bool string_to_number( const string& s, T& result )
  {
  // Try to transform that line into the result
  stringstream ss( s );
  ss >> result;

  // Indicate if it succeeded or failed
  return bool( ss );
  }

int main()
  {
  const int max_num_items = 100;

  int    id     [ max_num_items ];
  double balance[ max_num_items ];
  int    num_items;
  string s;

  cout << "Please enter the following requested information.\n"
          "Press ENTER without typing anything else to finish.\n\n";

  for (num_items = 0; num_items < max_num_items; num_items++)
    {
    cout << "Enter the customer's ID number: ";
    while (true)
      {
      // Users expect to have to press ENTER after each input, so read the whole line
      getline( ins, s );
      if (s.empty()) break;
      if (string_to_number( s, id[num_items] ) && (id[num_items] >= 1000) && (id[num_items] <= 9999)) break;
      cout << "You have entered an invalid ID.  Please try again: ";
      }
    if (s.empty()) break;

    cout << "Enter the customer's balance: ";
    while (true)
      {
      getline( ins, s );
      if (s.empty()) break;
      if (string_to_number( s, balance[num_items] ) && (balance[num_items] <= 9999)) break;
      cout << "You have entered an incorrect balance.  Please try again: ";
      }
    if (s.empty()) break;
    }
  cout << "Thank you.\n"
          "You have entered " << num_items << " items.\n\n"

          "Now to do some amazing math with them.\n\n";

  ...

  return 0;
  }

Hope this makes sense.