在C＃中获取和设置问题

Question

I am trying to assign a line of text as a string, so the string can be used in a message box, although the string fails to show up in the message box when the method is executed.

public string version { get; set; }

public void GetVersion()
{
    var version = File.ReadAllText("version.txt");
}


private void SetBalloonTip()
{
    notifyIcon1.Icon = SystemIcons.Exclamation;
    notifyIcon1.BalloonTipTitle = "Test";
    notifyIcon1.BalloonTipText = "This is version " + version;
    notifyIcon1.BalloonTipIcon = ToolTipIcon.Error;
    this.Click += new EventHandler(button1_Click);
}

Answer 1

Remove the var :

version = File.ReadAllText("version.txt");

By adding the var (or any variable type for that matter) you're creating local variable, while you want to assign the class member.

Happens to me too sometimes, and I see this as downside of C# as I would expect at least a warning when compiling such a thing.

Answer 2

You are declaring a local variable with "var version", which is separate from your property "version". Just replace "var version" with "this.version" or just "version".

Answer 3

var version = ... shadows the property with a local variable; meaning, the assignment is stored in a local variable named version , not the property named version .

this.version = ... will do what you want.

By the way, out of convention in C#, local variables begin with lowercase letters as you have, but properties begin with an uppercase letter -- conventions like these may help alleviate shadowing issues as you experienced here.

Answer 4

if you are using var here, you should also be aware of its purpose and implication. never use anything that you are not familiar with. This is just thumb rule.

As mentioned above, using proper casing for class member and accessing class member with this. are best practices.