Not keyword vs = False when checking for false boolean condition

Question

When I'm using an If statement and I want to check if a boolean is false should I use the "Not" keyword or just = false, like so

If (Not myboolean) then 

vs

If (myboolean = False) then

Which is better practice and more readable?

Answer 1

It does not make any difference as long you are dealing with VB only, however if you happen to use C functions such as the Win32 API, definitely do not use "NOT" just "==False" when testing for false, but when testing for true do not use "==True" instead use "if(function())".

The reason for that is the difference between C and VB in how boolean is defined.

1. In C true == 1 while in VB true == -1 (therefore you should not compare the output of a C function to true, as you are trying to compare -1 to 1)

2. Not in Vb is a bitwise NOT (equal to C's ~ operator not the ! operator), and thus it negates each bit, and as a result negating 1 (true in C) will result in a non zero value which is true, NOT only works on VB true which is -1 (which in bit format is all one's according to the two's complement rule [111111111]) and negating all bits [0000000000] equals zero.

For a better understanding see my answer on Is there a VB.net equivalent for C#'s ! operator?

Answer 2

Definitely, use "Not". And for the alternately, use "If (myboolean)" instead of "If (myboolean = true)"

The works best if you give the boolean a readable name:

 if (node.HasChildren)