terminating the loop with a negative number

[gghf]

I am making a function in a class where it asks the user to enter in numbers and to enter in a -1 when you are done with the list. I used the code below. The problem is that when they put a -1 to tell the program to stop collecting numbers, it stores -1 as a number in the array. How can I make it so -1 isnt stored? Thanks.

  void Numbers() {
		for (int i = 0; i < n; i++) {
			cin >> a[i];
			if (a[i] < 0) { break; }
		}
	}

[keskiverto]

Don't put a value directly into the array. Read, test, and then store.


You do have a second issue: How many values are in the array after the input loop?

[TwilightSpectre]

How about you store the value in a temporary value, and then check first? Here is an example:

void Numbers() {
    for (int i = 0; i < n; ++i) {
        int temp;
        cin >> temp;
        if (temp < 0) break;
        a[i] = temp;
    }
}

[long double main]

Depending on what your situation is, it might even be desirable to keep the negative number, as a way to mark the end of the input.

For instance:

int array[101]; // Plenty of elements
std::cout << "Enter up to 100 elements, and enter -1 when you are done: ";
for (int i = 0; i < 100; ++i)
{
    std::cin >> array[i];
    if (array[i] == -1)
        break;
}
array[100] = -1; // If the user entered 100 elements, this will mark the end of the input

std::cout << "Here's what you entered:\n";
for (int i = 0; array[i] != -1; ++i) // Use the -1 to know when to stop
    std::cout << array[i] << '\n';

[eyenrique]

are allowed negative numbers?

what if -1 is part of the set of numbers?

i.e.

Enter 5 numbers:
Number 1:  3
Number 2:  7
Number 3:  8
Number 4:  -1
Number 5:  -12

Numbers entered:
3,7,8,-1,-12

I have a different
example using
EOF end-of-file
character to stop
when you are
done;

Enter 10 numbers (ctrl+D to quit)
Enter number #1 :1
Enter number #2 :4
Enter number #3 :-1
Enter number #4 :5
Enter number #5 :-4
Enter number #6 :30
Enter number #7 :9
Enter number #8 :^D <-- EOF (ctrl+D Mac OS X)

Numbers entered:

1 4 -1 5 -4 30 9

//EnterNumbers.cpp
//##

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

int EnterNumbers(int array[],int const SIZE);
void PrintArray(int array[],int const INDEX);

int main(){

        int const SIZE=10;
        int index;
        int setNumbers[SIZE]={};

        index=EnterNumbers(setNumbers,SIZE);
        PrintArray(setNumbers,index);


return 0; //indicates success
}//end main

int EnterNumbers(int array[],int const SIZE){
        cout<<"Enter "<<SIZE<<" numbers (ctrl+D to quit)"<<endl;

        for(int i=0;i<SIZE;i++){
                cout<<"Enter number #"<<i+1<<" :";
                cin>>array[i];
                if(cin.eof()){
                        return i;
                }//end if
        }//end for

return SIZE;
}//end function EnterNumbers

void PrintArray(int array[],int const INDEX){
        cout<<endl;
        for(int i=0;i<INDEX;i++){
                cout<<array[i]<<((i+1)%10==0?'\n':' ');
        }//end for
cout<<endl;
}//end function PrintArray