从另一种形式调用函数C＃

Question

i have a main form with a function that changes the text of a text box thats on the main form, the code is below:

main form function:

    public void consoleLog(string message)
    {
        txtConsoleLog.Text += Environment.NewLine;
        txtConsoleLog.Text += message;
        txtConsoleLog.SelectionStart = txtConsoleLog.TextLength;
        txtConsoleLog.ScrollToCaret();
        txtConsoleLog.Refresh();
    }

So now i open a new form called frm connect when i click a button like this:

    private void connectToolStripMenuItem_Click(object sender, EventArgs e)
    {
        Form frmConnect = new FrmConnect(this);
        frmConnect.Show();
    }

this is the frmConnect below

public partial class FrmConnect : Form
{
    private Form mainForm;

    public FrmConnect(Form frmMain)
    {
        this.mainForm = frmMain;
        InitializeComponent();
    }

    private void btnConnect_Click(object sender, EventArgs e)
    {
        FrmMain.Connected = true;
        mainForm.consoleLog("Connected");
    }
}

So when i click a button i want to call the function but its saying it doesnt contain a definition for it, also im trying to change the 'Connected' variable thats on the main form which works by just referencing the FrmMain but am i able to do that using mainForm.Connected = true?

If i change the function to public static, it will work by referencing FrmMain but then i get errors with the txtConsoleLog as i cant reference an object in a non static method or something like that, any help is appriciated

Answer 1

When you pass the form into your constructor, and store it as the private member variable, in both places you declare it of the base type Form . In order to use a method on the type that you defined, your parameter and variable should be of type FrmMain .

public partial class FrmConnect : Form
{
    private FrmMain mainForm;

    public FrmConnect(FrmMain frmMain)
    {
        this.mainForm = frmMain;
        InitializeComponent();
    }

    private void btnConnect_Click(object sender, EventArgs e)
    {
        FrmMain.Connected = true;
        mainForm.consoleLog("Connected");
    }
}

Answer 2

You should change

private Form mainForm;

public FrmConnect(Form frmMain)
{

To

private FrmMain mainForm;

public FrmConnect(FrmMain frmMain)
{

which will later give you access to all of the public properties on FrmMain in your other methods in the FrmConnect class.