Best way to write function to count digits?

[birdwalkr]

This code finds the first,last and # of digits of an integer. Problem is using an if statement to find the # of digits only works up to nine digits. suggestions on a better way to do this?

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

int first_digit (int n)
{
    const int base = 10;
    int x;
    do
          {
          x = n % 10;
          }
      while (n /= base);
      return x;
}

int last_digit (int n)
{
    int x;
    {x = n % 10;}
    return x;
}

int digits (int n)
{
    n = abs(n);
    if (n < 10) return 1;
    else if (n < 100) return 2;
    else if (n < 1000) return 3;
    else if (n < 10000) return 4;
    else if (n < 100000) return 5;
    else if (n < 1000000) return 6;
    else if (n < 10000000) return 7;
    else if (n < 100000000) return 8;
    else if (n < 1000000000) return 9;
    else 
    return 10;
}

int main()
{int input;
cout << "Please enter a number: ";
cin >> input;
cout << "The first digit is ";
cout << first_digit (input) << endl;
cout << "The last digit is ";
cout << last_digit (input) << endl;
cout << input << " has " << digits (input) << " digit(s)." << endl;
system ("pause");
return 0;
}

[vlad from moscow]

int digits( int n )
{
    n = abs(n);

    int i = 0;
    do { i++; } while ( n /= 10 );

    return ( i );
}

[birdwalkr]

Works fine up until about twelve digits?

[vlad from moscow]

And what is the problem? By the way are you sure that objects of type int can have 12 digits on your system?

[ModShop]

At twelve digits you get close and/or reach the max size of an int (2³² on a 32 bit system, 2⁶⁴ on a 64 bit system). Use long long int or other larger data types for bigger numbers.

[cire]

#include <limits>

int main()
{
    std::cout << "The maximum number of decimal digits an int can hold on this system is "
        << std::numeric_limits<int>::digits10 << '\n' ;

    int input;
    cout << "Please enter a number: ";
    cin >> input;
    cout << "The first digit is ";
    cout << first_digit (input) << endl;
    cout << "The last digit is ";
    cout << last_digit (input) << endl;
    cout << input << " has " << digits (input) << " digit(s)." << endl;
    system ("pause");
    return 0;
}

[clanmjc]

That's the limitation of an integer on your system. Use long long and gain up to 19 digits.

[birdwalkr]

@ vlad
I'm running 64 bit I wasn't aware that made a difference and I was hoping to find a way to do it so It could find numbers past 12?

@ modshop
ah thanks this should help