simple i/o question

right, i'm having problems with something stupid involving input and arrays.

Code:

    char number[256];
    cout << "enter a number" << endl;
    cin.getline(number,256);
    cout << "the number is" << endl;
         for (int i = 0;i > ???;i++) {
             cout << number[i];
             }
    cout << endl;

what do i put in that red area to output the correct number?

I know that if i put in 256, and if the number entered has less than 256 digits, then the program messes up. how can i figure out which units in the array are being used?

i know this system isn't the way numbers are usually handled, but i'm doing something different involving very large numbers.

Code:

char number[256];
cout << "enter a number" << endl;
cin.getline(number,256);
cout << "the number is" << endl;
for (int i = 0;i < strlen(number);i++)
{
    cout << number[i];
}
cout << endl;