Question

I am facing a very strange problem and couldn’t figure out where’s the mistake. I’m using SendMessage_EX to get a specified line’s text:

SendMessage_Ex(hr.Handle, EM_GETLINE, l, buffer);

then I call the method twice like this:

StringBuilder buffer = new StringBuilder(256);
SendMessage_Ex(hr.Handle, EM_GETLINE, 5, buffer);
StringBuilder buffer1 = new StringBuilder(256);
SendMessage_Ex(hr.Handle, EM_GETLINE, 4, buffer1);

It gets text of line 5 correctly but then for line 4, It returns nothing(buffer1 is empty).
If I reverse it and first get line 4 and then line 5, It returns the text of line 4 and nothing for line 5.

It’s very strange and I’m sure I’m making a simple mistake, but where is the mistake?
I appreciate any help. 🙂

Answer 1

The EM_GETLINE message wants the size of the buffer passed in the same parameter it uses for a buffer. I couldn’t just set the 0 index of the StringBuilder without initializing it to some value (got an index exception).

This seems to work:

StringBuilder buffer = new StringBuilder("   ", 256);
buffer[0] = (char)256;   
int Result = SendMessage_Ex(textBox1.Handle, EM_GETLINE, 3, buffer);

StringBuilder buffer1 = new StringBuilder("   ", 256);
buffer1[0] = (char)256;
int Result1 = SendMessage_Ex(textBox1.Handle, EM_GETLINE, 2, buffer1);

MessageBox.Show(buffer.ToString());
MessageBox.Show(buffer1.ToString());