why foreach is faster than for loop while reading richtextbox lines

richtextbox

Solution

As Mehrdad noted, accessing the `Lines` property takes a long time. You need to be careful here - you're accessing it twice in each iteration at the moment:

String s = String.Empty;
for (int i = 0; i < richTextBox.Lines.Length; i++)
{
    s = richTextBox.Lines[i];
}

Even if you remove the access in the body of the loop like this:

String s = String.Empty;
for (int i = 0; i < richTextBox.Lines.Length; i++)
{
}

you're still accessing `Lines` on every iteration to see if you've finished!

If you don't want to `foreach`, you can just fetch `Lines` once:

string[] lines = richTextBox.Lines;
for (int i = 0; i < lines.Length; i++)
{
    s = lines[i];
}

Personally I prefer the `foreach` unless you really need the index though :)

Problem

There are two ways to read data from RichTextBox line by line 1 ) use a for loop to loop through lines of a richtextBox ``` String s=String.Empty; for(int i=0;i<richtextbox.lines.length;i++) { s=richTextBox.Lines[i] } ``` 2 ) use a foreach loop to enumerate richTextBox.Lines collection ``` String s=String.Empty; foreach(string str in txtText.Lines) { s=str; } ``` There is a huge difference in performance when we use foreach loop to enumerate array collection for richtextbox. I tried with 15000 lines.for loop took 8 minutes to just loop down to 15000 lines.while foreach took fraction of a second to enumerate it. Why is this behaviour there?

Original source