can't use SendMessage_EX twice in my c# program

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:

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());