How to swap a 2 digit number and find the larger of the result?-CodePudding

I want to use the number 25 then swap the two digits (the 2 and the 5) and then compare the swapped number (52) to the first number (25). If the swapped number is bigger I get a true and if the swapped number is smaller than the first number I get a false.

Example of what I want:

Input:

Output:

True //Because 25 reversed is 52, so it´s bigger

This is what I've tried:

        int firstdigit = num / 10;
        int secondigit = num % 10;
        string res = secondigit   firstdigit.ToString();
        
        if(res > num)
        {
            return true;
        }
        return false;

The problem now is that the "if" is not working anymore because res is a string and num is an int, but when I make res an int then I cant add the first digit and second digit because it's obviously different if I do 5 2 with ints (7) or 5 2 with strings (52).

CodePudding user response：

You need to construct the reversed int value and compare against that:

int firstdigit = num / 10;
int secondigit = num % 10;
int reversed   = firstdigit   seconddigit * 10;

if (reversed > num)
    ...

If you look at the code above, you should see that it's just reversing the logic that you used to extract the first and second digits.

CodePudding user response：

Constructing int from the beginning works (as answered by others already), and probably is more efficient, but since you asked this question - you might be interested in this guide.

https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/types/how-to-convert-a-string-to-a-number

So you can convert your constructed string back to number to be able to compare it.