Friday, December 21, 2007 1:58 PMDoes the C# language definition guarantee that in the line
if ( func_one() && func_two() )
1) func_one() will be executed first
2) func_two() will only be executed if and only if func_one() returns true
My C# book evades the issue.
Friday, December 21, 2007 2:12 PMModerator
Yes C# does short circuit evaluation of boolean expressions. Therefore in any boolean expression of type x op y, x is evaluated first and y is evaluated only if it is meaningful to do so. In the case of an AND operation if x is false then y is not evaluated. For OR if x is true then y is not evaluated.
This applies to all boolean expressions and not just those in an IF statement. This is covered under section 14.11.1 of the C# Specification available online at MSDN.
Michael Taylor - 12/21/07
Friday, December 21, 2007 2:45 PM
yes that's rigth this brief example can prove it.Code Snippet
}static void Main(string args)
if (method1(true) && method1(false))
try to compile in visual studio, csc, or mono compiler and the result should be exactly the same.
Friday, December 21, 2007 3:15 PMThank you both.
I realise that it does evaluate them in order, but I wanted this future-proofed and portable. I had a nasty experience with a language called Powerbuilder that did not guarantee the order - at least not then.
The expression I needed was 'short-circuit'. I have now found the section in Hejlsberg, Wiltamuth, Gold - the ultimate bathroom reader.
The forums today are sufficiently slow that I can get a decent amount of work donw while waiting for something to post. (Or is it just me?)
Saturday, December 22, 2007 12:02 AMIf you key VS2005 help Index for && symbol the explanation will be explicitly as to what you outlined in the first post.