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In what situations would I specify operation as unchecked?

Tags:

c#

math

unchecked

For example:

int value = Int32.MaxValue;

unchecked
{
    value += 1;
}

In what ways would this be useful? can you think of any?

like image 542
MasterMastic Avatar asked Sep 27 '11 12:09

MasterMastic


1 Answers

Use unchecked when:

  • You want to express a constant via overflow (this can be useful when specifying bit patterns)
  • You want arithmetic to overflow without causing an error

The latter is useful when computing a hash code - for example, in Noda Time the project is built with checked arithmetic for virtual everything apart from hash code generation. When computing a hash code, it's entirely normal for overflow to occur, and that's fine because we don't really care about the result as a number - we just want it as a bit pattern, really.

That's just a particularly common example, but there may well be other times where you're really happy for MaxValue + 1 to be MinValue.

like image 61
Jon Skeet Avatar answered Oct 18 '22 20:10

Jon Skeet