CODEWITHSUNDEEP
c#.netwinformseventstextbox
Jack
Jack

Reputation: 16724

how to append text to lines of texbox?

I'm using the following code in _TextChanged:

string[] currentLines = new string[text.Lines.Length];
for (int i = 0; i < currentLines.Length; i++) {
       currentLines[i] = text.Lines[i] + "...";
}

text.Lines = currentLines;

that's crashing when event is called. I have no idea how to fix this, the crash occurring when I do this:

text.Lines = currentLines;

why's that and how to fix? Thanks in advance.

Upvotes: 1

Views: 284

Answers (4)

Jack
Jack

Reputation: 16724

The solution:

For a reason that I don't know(if you know, explain for me, please), this crash occurs only with TextBox, I replaced to a RichTextBox and it works fine now.

Upvotes: 0

ispiro
ispiro

Reputation: 27713

Perhaps try unsubscribing from the _TextChanged event before the problematic line, and re-subscribing after it.

Upvotes: 0

Adam S
Adam S

Reputation: 3125

Setting Lines may trigger the _TextChanged event again. What is the error you are getting? If you see a StackOverflowException, this is the cause.

You could possibly add this to get around the problem, or take the bool flag approach Daniel mentioned in his answer.

text.TextChanged -= textBox1_TextChanged;

text.Lines = currentLines;

text.TextChanged += textBox1_TextChanged;

Also, perhaps this question discussing the difference between programmatic changes and user driven changes is of interest to you.

Upvotes: 4

Daniel Hilgarth
Daniel Hilgarth

Reputation: 174417

As Adam S notes in his answer, you are most likely getting a StackOverflowException because of endless recursion. You can try to fix it like this:

private void _TextChanged(...)
{
    static bool settingLines = false;
    if(settingLines)
        return;

    string[] currentLines = new string[text.Lines.Length];
    for (int i = 0; i < currentLines.Length; i++) {
           currentLines[i] = text.Lines[i] + "...";
    }

    settingLines = true;

    text.Lines = currentLines;

    settingLines = false;
}

This solution is not thread safe but that is not a problem in your case as you are interacting with UI controls anyway.

Upvotes: 1

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