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Whether the error handling of VB.NET affects the running speed, many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can get something.

When using any language for program development, we usually deal with the errors that will inevitably occur in the program development. Then in VB.NET, VB.NET error handling often has a certain impact on the running speed. On Error in VB.NET is used to catch and handle errors, and On Error Resume Next is often used to ignore errors that may occur.

So does the use of error trapping affect speed?

Yes, using VB.NET error handling will degrade some performance in. In Net, using Try Catch will also affect performance, so when we use Reflector to decompile Microsoft's class library, we will find that its subprocess rarely uses Try to catch errors, basically in a predictable way to judge possible errors and deal with them accordingly.

In fact, after using error trapping, the compiled code actually does a lot of operations that are not known to us. Although using error trapping facilitates the coding process to a certain extent, it sacrifices a certain speed, which has both advantages and disadvantages. So we should use error trapping correctly.

VB.NET tested

Option Explicit

Dim cn As New ADODB.Connection

Dim rs As New ADODB.Recordset

Dim m_FldsName () As String

Private Sub Command1_Click ()

Dim II As Long

Dim t As Single

Cn.Open "Provider=SQLOLEDB.1;Persist

Security Info=False;User ID=sa;Initial

Catalog= merchants; Data Source=SUPER "

Rs.Open "Select * from FldSet"

Cn, adOpenKeyset

Do Until rs.EOF = True

Rs.MoveNext

Loop

Rs.MoveFirst

T = Timer

ReDim m_FldsName (rs.Fields.Count)

For II = 0 To rs.Fields.Count-1

M_FldsName (II) = rs.Fields (II) .Name

Next

Do Until rs.EOF = True

ReadFieldsNotOnErr "Err1"

ReadFieldsNotOnErr "TableName"

ReadFieldsNotOnErr "Err2"

Rs.MoveNext

Loop

MsgBox "NotErr:" & Timer-t

On Error Resume Next

Rs.MoveFirst

T = Timer

Do Until rs.EOF = True

ReadFieldsOnErr "Err1"

ReadFieldsOnErr "TableName"

ReadFieldsOnErr "Err2"

Rs.MoveNext

Loop

MsgBox "OnErr:" & Timer-t

Rs.Close

Cn.Close

End Sub

Private Sub ReadFieldsOnErr

(FieldName As String)

Dim v As Variant

V = rs (FieldName) .Value

End Sub

Private Sub ReadFieldsNotOnErr

(FieldName As String)

Dim II As Long

Dim IsExists As Boolean

Dim v As Variant

IsExists = False

For II = 0 To UBound (m_FldsName)-1

If m_FldsName (II) = FieldName Then

IsExists = True

Exit For

End If

Next

If IsExists = True Then

V = rs (FieldName) .Value

End If

End Sub

Test results:

When there are no errors

ReadFieldsOnErr: 0 . 46 ReadFieldsNotOnErr: 0 . forty-seven

When there is a mistake

ReadFieldsOnErr: 0.96 ReadFieldsNotOnErr: 0.47

As you can see: without VB.NET error handling, the speed is quite stable, but when using VB.NET error handling, the speed drop is larger when there are errors. Therefore, for sub-procedures that are called frequently in the loop, it is recommended to preprocess the errors that may occur to reduce the use of On error to improve speed.

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