How to bubble sort a string array?

Question

public void BubbleSortArrayString(string[] letters) //change here
{
    bool swap;
    string temp; //change this too

    do
    {
        swap = false;

        for (int index = 0; index < (letters.Length - 1); index++)
        {
            if (letters[index] > letters[index + 1]) //if first number is greater then second then swap
            {
                //swap

                temp = letters[index];
                letters[index] = letters[index + 1];
                letters[index + 1] = temp;
                swap = true;
            }
        }

    } while (swap == true);
}

I have managed to bubble sort a decimal but I'm suck with a string, I have a text file with months in it and I need to sort it in alphabetical order. I get the error:

operator > cannot be applied to type string and string

Help would be appreciated.

FYI: == true is unnecessary since it is just evaluating whether your boolean value equals another boolean value to return a boolean value, since you already have a boolean value to start with you can just use that (while(swap)) — Sayse
– Sayse, Commented Apr 21, 2016 at 9:03

Valentin · Accepted Answer · 2016-04-21 08:53:58Z

5

You can use string.Compare(x,y) instead of <, which returns 0 if the string are equal, otherwise an integer that indicates their relative position in the sort order

    for (int index = 0; index < (letters.Length - 1); index++)
    {
        if (string.Compare (letters[index], letters[index + 1]) < 0) //if first number is greater then second then swap
        {
            //swap

            temp = letters[index];
            letters[index] = letters[index + 1];
            letters[index + 1] = temp;
            swap = true;
        }
    }

If you want to ignore case during the comparison, you should use string.Compare (letters[index], letters[index + 1], true)

edited Apr 21, 2016 at 8:53

answered Apr 21, 2016 at 8:49

Valentin

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1 Comment

georgeThornton96 Over a year ago

Thank you so much!

Salah Akbari · Accepted Answer · 2016-04-21 09:21:53Z

0

You could use String.CompareOrdinal for strings. Also it would be better if you invert your if statement to reduce nesting. Like this:

if (String.CompareOrdinal(letters[index], letters[index + 1]) >= 0) continue;                    
temp = letters[index];
letters[index] = letters[index + 1];
letters[index + 1] = temp;
swap = true;

From MSDN:

This method performs a case-sensitive comparison using ordinal sort rules. For more information about word, string, and ordinal sorts, see System.Globalization.CompareOptions. To perform a case-insensitive comparison using ordinal sort rules, call the Compare(String, String, StringComparison) method with the comparisonType argument set to StringComparison.OrdinalIgnoreCase.

edited Apr 21, 2016 at 9:21

answered Apr 21, 2016 at 8:51

Salah Akbari

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