Which one is performance wise to clear a string builder?

Question

Q :

Which one is performance wise : to clear a string builder

AStringBuilder.Remove(0,AStringBuilder.Length);

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string theString = AStringBuilder.ToString();
ABuilder.Replace(theString,String.Empty);

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AStringBuilder.Length = 0;

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Note : I use Framework 3.5 which doesn't contain Clear() method.

Answer 1

Update It turns out that you are using .net 3.5 and Clear was added in .net 4. So you should use Length = 0. Actually I'd probably add an extension method named Clear to do this since it is far more readable, in my view, than Length = 0.

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I would use none of those and instead call Clear.

Clear is a convenience method that is equivalent to setting the Length property of the current instance to 0 (zero).

I can't imagine that it's slower than any of your variants and I also can't imagine that clearing a StringBuilder instance could ever be a bottleneck. If there is a bottleneck anywhere it will be in the appending code.

If performance of clearing the object really is a bottleneck then you will need to time your code to know which variant is faster. There's never a real substitute for benchmarking when considering performance.