How to Efficiently Insert Spaces Before Capital Letters in a String?

Insert Spaces before Capital Letters

When dealing with text that contains upper and lowercase letters, it is often desirable to separate words by adding spaces before capital letters. This can improve readability and make it easier to distinguish between different words.

Regex Method

One common approach is to use a regular expression to search for and replace capital letters preceded by lowercase letters. The following regex will match all capital letters preceded by a lowercase letter:

[A-Z]

To insert a space before these capital letters, you can use the following replacement pattern:

\s<pre class="brush:php;toolbar:false">System.Text.RegularExpressions.Regex.Replace(value, "[A-Z]", "\s<pre class="brush:php;toolbar:false">string AddSpacesToSentence(string text, bool preserveAcronyms)
{
        if (string.IsNullOrWhiteSpace(text))
           return string.Empty;
        StringBuilder newText = new StringBuilder(text.Length * 2);
        newText.Append(text[0]);
        for (int i = 1; i < text.Length; i++)
        {
            if (char.IsUpper(text[i]))
                if ((text[i - 1] != ' ' && !char.IsUpper(text[i - 1])) ||
                    (preserveAcronyms && char.IsUpper(text[i - 1]) && 
                     i < text.Length - 1 && !char.IsUpper(text[i + 1])))
                    newText.Append(' ');
            newText.Append(text[i]);
        }
        return newText.ToString();
}

")

This replacement pattern uses the s character class to insert a space before the matching capital letter, while $0 represents the matching substring. Here is an example using this regex:

Manual Method

While regexes can be effective, they can also be complex and expensive in terms of performance. An alternative approach is to manually iterate through the string character by character and insert spaces as needed. The following code snippet demonstrates this method:

This code iterates through each character in the string and checks if it is uppercase. If it is, and it is preceded by a lowercase letter (unless the preserveAcronyms parameter is set to true and the previous character is also uppercase), a space is inserted.

Performance Considerations

The regex method can be significantly slower than the manual method, particularly for large strings. However, the manual method is more complex and may be less readable for some developers. Ultimately, the best choice between these two methods depends on the performance requirements and readability preferences of your specific project.

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