帮助为vb.net创建功能 [英] Help creating functions for vb.net

问题描述

我一直在尝试学习如何创建自己的功能，并且需要一些帮助.我创建的每个人都会收到类似的警告，如下所示:

I have been trying t learn how to create my own funtions and need a little help. On everyone i have created i get similar warnings like this:

Warning	1	Function ''GetFileContents'' doesn''t return a value on all code paths. A null reference exception could occur at run time when the result is used.	C:\Users\Zachary\Desktop\Synergy.079s\Synergy\Modules\Updating.vb	42	5	Synergy

这是我应该担心的事情，因为它可以工作，还是我应该在函数中添加一些东西以确保安全?帮助将是巨大的.

Is this something i shouldn''t worry about since it works or should i be adding something to the function for a safety? help would be great.

Public Function GetFileContents(ByVal FullPath As String, Optional ByRef ErrInfo As String = "") As String

    Dim strContents As String
    Dim objReader As StreamReader

    Try
        objReader = New StreamReader(FullPath)
        strContents = objReader.ReadToEnd()
        objReader.Close()
        Return strContents
    Catch Ex As Exception
        ErrInfo = Ex.Message
    End Try

End Function

推荐答案

您的代码的Catch部分不包含return语句.

我将更改您的代码，并在函数末尾更改更多return语句.

The Catch part of your code does not contain a return statement.

I would change your code and more the return statement at the end of the function.

Public Function GetFileContents(ByVal FullPath As String, Optional ByRef ErrInfo As String = "") As String

    Dim strContents As String = ""
    Dim objReader As StreamReader

    Try
        objReader = New StreamReader(FullPath)
        strContents = objReader.ReadToEnd()
        objReader.Close()
    Catch Ex As Exception
        ErrInfo = Ex.Message
    End Try

    Return strContents

End Function

这样，所有执行路径都会返回一个值.

This way all execution paths return a value.

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