Question: Get the difference for the largest and smallest number in a positive integer

[ZhuZhu]

Create a function to get the difference for the largest and smallest number in a positive number. For example integer 98721, the difference is 9 - 1, so the function would return 8. I have written this to solve it, but wonder if there is a better way of solving this problem. No array anyway, this question doesn't allow me to use array, only loop, if else and function.

  int differenceMaxMin (int);
  
  int main()
  {
     int n;
     cout << "Enter a positive integer: "
     cin >> n;

     cout << "The differences of the largest and smallest number is: "
          << int differenceMaxMin (n) << endl;

  }
  
  int differenceMaxMin (int n)
  {
     int lastD, nextD, max, min;
     lastD = n % 10;
     max = lastD;
     n = n / 10;
     nextD = n % 10;
     min = nextD;
     
     while (n > 0)
     {
        if (max < nextD)
           max = nextD;
        else if (min > nextD)
           min = nextD;
         
        n = n / 10;
        nextD = n % 10;   

     }
     return (max - min)
  }

[Repeater]

Line 10 is wrong. Don't specify the return type of a function when you use it. Only when you define the function.

You are unfortunately restricted in what you're permitted to use; making use of C++, you could do something like this:

     string n;
     cout << "Enter a positive integer: "
     cin >> n;

     cout << '\n' << *std::max_element(n.begin(), n.end()) - *std::min_element(n.begin(), n.end());

Under the restrictions you have, looping through the value to find the max and min is about all you can do.

[ZhuZhu]

@Repeater, oops should be differenceMaxMin (n) right?

[JLBorges]

#include <algorithm>

unsigned int max_digit( unsigned int n )
{
    if( n < 10 ) return n ;
    else return std::max( n%10, max_digit(n/10) ) ;
}

unsigned int min_digit( unsigned int n )
{
    if( n < 10 ) return n ;
    else return std::min( n%10, min_digit(n/10) ) ;
}

unsigned int diff_max_min_digits( unsigned int n )
{ return max_digit(n) - min_digit(n) ; }