VB.Net CType vs. Convert & C# Casting vs. Convert

[Logan X via .NET 247]

It's official....Con vert blows.

I ran a number of tests converting a double to an integer usingboth Convert & CType. I *ASSUMED* that CType would piggy-back ontop of Convert, and that performance would be identical.

I was 100% incorrect.

The code below produces the results:
CType Took: 0.2187528 seconds.
Convert Took: 12.187656 seconds.

Option Explicit On
Option Strict On

Module ConversionTest

Private Const STORED_VALUE As Double = 100000000
Sub Main()

TestCType()
TestConvert()

Console.ReadLin e()
End Sub

Private Sub TestCType()
Dim l_Time As Long = 0
Dim l_Converted As Integer = 0

l_Time = DateTime.Now.Ti cks
For l_LoopCounter As Integer = 0 To 100000000
l_Converted = CType(STORED_VA LUE, Integer)
Next
l_Time = DateTime.Now.Ti cks - l_Time
Console.WriteLi ne("Took " & (l_Time / 10000000) & "seconds.")

End Sub
Private Sub TestConvert()
Dim l_Time As Long = 0
Dim l_Converted As Integer = 0

l_Time = DateTime.Now.Ti cks
For l_LoopCounter As Integer = 0 To 100000000
l_Converted = Convert.ToInt32 (STORED_VALUE)
Next
l_Time = DateTime.Now.Ti cks - l_Time
Console.WriteLi ne("Took " & (l_Time / 10000000) & "seconds.")
End Sub

End Module

The IL is VERY different. It appears as though the Convert iscreating a local copy of the Const variable per loop. Is thiscorrect? Does Convert take into account globalization? (Thatwould certainly explain the delay) If you change the conversionto act against the l_LoopCounter then the performance differencenarro ws substantially, BUT Convert is still far behind.

It seems that in *ALL* cases, CType > Convert. (This *ALSO* holdstrue in C#.)

Thank you.


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From: Logan X

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Posted by a user from .NET 247 (http://www.dotnet247.com/)

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