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copied!<p>The regexes will work fine (I even voted up Martin Browns answer), but they are expensive (and personally I find any pattern longer than a couple of characters prohibitively obtuse)</p> <p>This function </p> <pre><code>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(); } </code></pre> <p>Will do it 100,000 times in 2,968,750 ticks, the regex will take 25,000,000 ticks (and thats with the regex compiled).</p> <p>It's better, for a given value of better (i.e. faster) however it's more code to maintain. "Better" is often compromise of competing requirements.</p> <p>Hope this helps :)</p> <p><strong>Update</strong><br> It's a good long while since I looked at this, and I just realised the timings haven't been updated since the code changed (it only changed a little).</p> <p>On a string with 'Abbbbbbbbb' repeated 100 times (i.e. 1,000 bytes), a run of 100,000 conversions takes the hand coded function 4,517,177 ticks, and the Regex below takes 59,435,719 making the Hand coded function run in 7.6% of the time it takes the Regex.</p> <p><strong>Update 2</strong> Will it take Acronyms into account? It will now! The logic of the if statment is fairly obscure, as you can see expanding it to this ...</p> <pre><code>if (char.IsUpper(text[i])) if (char.IsUpper(text[i - 1])) if (preserveAcronyms && i < text.Length - 1 && !char.IsUpper(text[i + 1])) newText.Append(' '); else ; else if (text[i - 1] != ' ') newText.Append(' '); </code></pre> <p>... doesn't help at all!</p> <p>Here's the original <em>simple</em> method that doesn't worry about Acronyms</p> <pre><code>string AddSpacesToSentence(string text) { if (string.IsNullOrWhiteSpace(text)) return ""; StringBuilder newText = new StringBuilder(text.Length * 2); newText.Append(text[0]); for (int i = 1; i < text.Length; i++) { if (char.IsUpper(text[i]) && text[i - 1] != ' ') newText.Append(' '); newText.Append(text[i]); } return newText.ToString(); } </code></pre>

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