CODEWITHSUNDEEP
c#variablesscope
user2440720
user2440720

Reputation:

Variable not being seen in C# code

Learning C# and hit a snag.

Why isn't the variable 'number' used here?

    public partial class Form1 : Form
    {

    static string labelText = "";
    static string number = "";

    public Form1()                                  
    {
        InitializeComponent();
    }

    private void serialNumber_TextChanged(object sender, EventArgs e)
    {
        string number = this.serialNumber.Text;
    }

I keep getting a warning that field 'number' is assigned but not used.

Upvotes: 0

Views: 138

Answers (7)

Mihai
Mihai

Reputation: 13

It happens because of the string in the instruction string number = this.serialNumber.Text;, which is declaring a new variable, different from the class field, despite having the same name. Remove the string modifier and the instruction will refer to the class field already declared.

Upvotes: 0

Azhar Khorasany
Azhar Khorasany

Reputation: 2709

Change these lines:

static string number = "";

private void serialNumber_TextChanged(object sender, EventArgs e)
{
    string number = this.serialNumber.Text;
}

to 

private string number = "";

private void serialNumber_TextChanged(object sender, EventArgs e)
{
    number = this.serialNumber.Text;
}

Upvotes: 1

DonBoitnott
DonBoitnott

Reputation: 11035

First off, the warning is valid, and relates to the static member, which, in fact, is assigned and never used. The one in serialNumber_TextChanged is local to that method and by definition, different.

This: "Why isn't the variable 'number' used here?"...I do not understand.

Upvotes: 0

Dirk
Dirk

Reputation: 10968

In your serialNumber_TextChanged method you declare a local variable called number. So if that is your complete code you never actually assign anything to Form1.number apart of the static initialization.

Upvotes: 1

Dark Falcon
Dark Falcon

Reputation: 44201

string number declares a new local variable which hides the static member variable.

Upvotes: 2

Paolo Tedesco
Paolo Tedesco

Reputation: 57272

That's exactly what's happening: you are assigning a value to the variable number, and then you don't do anything with that variable.

Upvotes: 0

Kurubaran
Kurubaran

Reputation: 8902

string number = this.serialNumber.Text; this line creates a new string.

try this to avoid the warning

public partial class Form1 : Form {

static string labelText = "";
static string number = "";

public Form1()                                  
{
    InitializeComponent();
}

private void serialNumber_TextChanged(object sender, EventArgs e)
{
    number = this.serialNumber.Text;
}

Upvotes: 3

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