Is it Better to Use [Type].Parse or C[Type]

Question

If I try to put a string into a Boolean variable such as this:

    Dim testValue As String = "True"
    Dim bool1 As Boolean = testValue

With Option Strict On I get an error and the suggested fix is to change the second line to:

    Dim bool1 As Boolean = CBool(testValue)

This is fine, But - what are the advantages / disadvantages of doing this instead:

    Dim bool1 As Boolean = Boolean.Parse(testValue)

CBool feels very VB6 like to me but which should we be using and why?

Answer 1

If you know its a string in both cases, it should be an equivalent process. Since Cbool will eventually call a function to convert it. (As long as your value is "True" or "False")

There is a difference if you use something like cbool(value) and the value is a boolean.

from MSDN:

Note that the parse operation succeeds only if the string to be parsed is "True" (the value of the TrueString field) or "False" (the value of the FalseString field) in a case-insensitive comparison.

From MSDN in regards to Cbool (and other methods like that):

These functions are compiled inline, meaning the conversion code is part of the code that evaluates the expression. Sometimes there is no call to a procedure to accomplish the conversion, which improves performance. Each function coerces an expression to a specific data type

So, if you use cbool(value) if your value is a boolean it just uses it, no conversion required. That makes it potentially more efficient.

You can check this out too: Integer.Parse vs. CInt

Answer 2

I think the big difference is that Boolean.Parse is very strict about what it will accept (true/false) where as CBool is more lenient (0/1, true/false, I think yes/no although I'd have to retest that).

If you are ever going to port the code to C# or know that you will only ever have true/false values, then Parse would be the way to go. Otherwise, I would use CBool for its added flexibility.