修剪十分之一的数字的算法

Question

I need to detect which word I need to display that is correspond to the user score.

I have next switch:

switch (score) {
        case 0:
            outString = @"String1";
            break;
        case 1:
            outString = @"String2";
            break;
        case 2:
            outString = @"String3";
            break;
        case 3:
            outString = @"String3";
            break;
        case 4:
            outString = @"String3";
            break;
        case 5:
            outString = @"String1";
            break;
        case 6:
            outString = @"String1";
            break;
        case 7:
            outString = @"String1";
            break;
        case 8:
            outString = @"String1";
            break;
        case 9:
            outString = @"String1";
            break;           

        default:
            break;
    }

But, how I can use the same switch when score will be 29 or 109. So I need to trim in the first case 20 to get 9 and in the second case I need to trim 100 to get 9.

I used this algorithm before, but I forgot how to :(

So the goals is next - I every time need just number from 0 - 9 without tenths hundredths thousandths numbers.

Answer 1

If your word always depends on last digit of number, you can simply use it in switch condition (using modulus operator):

switch (score % 10)
   ...

If only 29 and 129 are special cases then you can use multiple labels for the same case:

case 9:
case 29:
case 109:
        outString = @"String1";
        break;

Answer 2

Much better than to use a giant switch statement, is to use a lookup table:

std::string score_string(unsigned int score)
{
    static const std::string strings = {"String1","String2","String3",...};
    static const int strings_count = 10; //10 strings in the lookup table, for example.

    return strings[score % strings_count];
}