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In c#, is there any difference in the excecution speed for the order in which you state the condition?
if (null != variable) ... if (variable != null) ... Since recently, I saw the first one quite often, and it caught my attention since I was used to the second one.
If there is no difference, what is the advantage of the first one?
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If the operands of an equality operator are both of either reference type or the null type, then the operation is object equality. The result of != is false if the operand values are both null or both refer to the same object or array; otherwise, the result is true . Use whatever is most readable.
The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables. Ordinary value types cannot be null, except for nullable value types. The following example demonstrates some behaviors of the null keyword: C# Copy.
To set the value of a variable is it's equal to null , use the nullish coalescing operator, e.g. myVar = myVar ?? 'new value' . The nullish coalescing operator returns the right-hand side operand if the left-hand side evaluates to null or undefined , otherwise it returns the left-hand side operand.
The null value simply means that the variable does not refer to an object in memory.
It's a hold-over from C. In C, if you either use a bad compiler or don't have warnings turned up high enough, this will compile with no warning whatsoever (and is indeed legal code):
// Probably wrong if (x = 5) when you actually probably meant
if (x == 5) You can work around this in C by doing:
if (5 == x) A typo here will result in invalid code.
Now, in C# this is all piffle. Unless you're comparing two Boolean values (which is rare, IME) you can write the more readable code, as an "if" statement requires a Boolean expression to start with, and the type of "x=5" is Int32, not Boolean.
I suggest that if you see this in your colleagues' code, you educate them in the ways of modern languages, and suggest they write the more natural form in future.
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