Question

I have a large string, where there can be specific words (text followed by a single colon, like “test:”) occurring more than once. For example, like this:

word:
TEST:
word:

TEST:
TEST: // random text

“word” occurs twice and “TEST” occurs thrice, but the amount can be variable. Also, these words don’t have to be in the same order and there can be more text in the same line as the word (as shown in the last example of “TEST”). What I need to do is append the occurrence number to each word, for example the output string needs to be this:

word_ONE:
TEST_ONE:
word_TWO:

TEST_TWO:
TEST_THREE: // random text

The RegEx for getting these words which I’ve written is ^\b[A-Za-z0-9_]{4,}\b:. However, I don’t know how to accomplish the above in a fast way. Any ideas?

Answer 1

Regex is perfect for this job – using Replace with a match evaluator:

This example is not tested nor compiled:

public class Fix
{
    public static String Execute(string largeText)
    {
        return Regex.Replace(largeText, "^(\w{4,}):", new Fix().Evaluator);
    }

    private Dictionary<String, int> counters = new Dictionary<String, int>();
    private static String[] numbers = {"ONE", "TWO", "THREE",...};
    public String Evaluator(Match m)
    {
        String word = m.Groups[1].Value;
        int count;
        if (!counters.TryGetValue(word, out count))
          count = 0;
        count++;
        counters[word] = count;

        return word + "_" + numbers[count-1] + ":";
    }
}

This should return what you requested when calling:

result = Fix.Execute(largeText);