AutoComplete Brackets In C#.NET/VB .NET

Step 1: Start Visual Studio and create Windows Form Application in C# or VB as you wish.

Step 2: Add CheckBox and RichTextBox to your form.

Step 3: Add KeyPress and KeyDown events to RichTextBox.

Step 4: Now add the following code defined in KeyPress and KeyDown event into your code.

How it Works

It's simple, just identify which key is pressed in richTextBox, if it is ( open round bracket then read SelectionStart from richTextBox and insert opposite character to richTextBox at position SelectionStart+1.

Finally add one line once opposite character is inserted and that is e.Handled=true;

C# Code for Auto Complete Brackets,

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
namespace Auto_Complete_Brackets
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
//declare isCurslyBracesKeyPressed variable as Boolean and assign false value
//to check { key is pressed or not
public static Boolean isCurslyBracesKeyPressed = false;
//richTextBox1 KeyPress events
// if key (,{,<,",',[ is pressed then insert opposite key to richTextBox1 at Position SelectionStart+1
// add one line after inserting, e.Handled=true;
//finally set SelectionStart to specified position
private void richTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
String s = e.KeyChar.ToString();
int sel = richTextBox1.SelectionStart;
if (checkBox1.Checked == true)
{
switch (s)
{
case "(": richTextBox1.Text = richTextBox1.Text.Insert(sel, "()");
e.Handled = true;
richTextBox1.SelectionStart = sel + 1;
break;
case "{":
String t = "{}";
richTextBox1.Text = richTextBox1.Text.Insert(sel, t);
e.Handled = true;
richTextBox1.SelectionStart = sel + t.Length - 1;
isCurslyBracesKeyPressed = true;
break;
case "[": richTextBox1.Text = richTextBox1.Text.Insert(sel, "[]");
e.Handled = true;
richTextBox1.SelectionStart = sel + 1;
break;
case "<": richTextBox1.Text = richTextBox1.Text.Insert(sel, "<>");
e.Handled = true;
richTextBox1.SelectionStart = sel + 1;
break;
case "\"": richTextBox1.Text = richTextBox1.Text.Insert(sel, "\"\"");
e.Handled = true;
richTextBox1.SelectionStart = sel + 1;
break;
case "'": richTextBox1.Text = richTextBox1.Text.Insert(sel, "''");
e.Handled = true;
richTextBox1.SelectionStart = sel + 1;
break;
}
}
}
// richTextBox1 Key Down event
/*
* when key { is pressed and {} is inserted in richTextBox
* and isCurslyBracesKeyPressed is true then insert some blank text to richTextBox1
* when Enter key is down
* it will look like this when Enter key is down
{
|
}
* */
private void richTextBox1_KeyDown(object sender, KeyEventArgs e)
{
int sel = richTextBox1.SelectionStart;
if (e.KeyCode == Keys.Enter)
{
if(isCurslyBracesKeyPressed==true)
{
richTextBox1.Text = richTextBox1.Text.Insert(sel, "\n \n");
e.Handled = true;
richTextBox1.SelectionStart = sel + " ".Length;
isCurslyBracesKeyPressed = false;
}
}
}
}
}

VB.Net Code for Auto Complete Brackets

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Windows.Forms
Public Class Form1
'declare isCurslyBracesKeyPressed variable as Boolean and assign false value
'to check { key is pressed or not
Public Shared isCurslyBracesKeyPressed As [Boolean] = False
'RichTextBox1 KeyPress events
' if key (,{,<,",',[ is pressed then insert opposite key to RichTextBox1 at Position SelectionStart+1
' add one line after inserting, e.Handled=true;
'finally set SelectionStart to specified position
Private Sub RichTextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles RichTextBox1.KeyPress
Dim s As [String] = e.KeyChar.ToString()
Dim sel As Integer = RichTextBox1.SelectionStart
If checkBox1.Checked = True Then
Select Case s
Case "("
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, "()")
e.Handled = True
RichTextBox1.SelectionStart = sel + 1
Exit Select
Case "{"
Dim t As [String] = "{}"
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, t)
e.Handled = True
RichTextBox1.SelectionStart = sel + t.Length - 1
isCurslyBracesKeyPressed = True
Exit Select
Case "["
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, "[]")
e.Handled = True
RichTextBox1.SelectionStart = sel + 1
Exit Select
Case "<"
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, "<>")
e.Handled = True
RichTextBox1.SelectionStart = sel + 1
Exit Select
Case """"
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, """""")
e.Handled = True
RichTextBox1.SelectionStart = sel + 1
Exit Select
Case "'"
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, "''")
e.Handled = True
RichTextBox1.SelectionStart = sel + 1
Exit Select
End Select
End If
End Sub
' RichTextBox1 Key Down event
'
' * when key { is pressed and {} is inserted in richTextBox
' * and isCurslyBracesKeyPressed is true then insert some blank text to RichTextBox1
' * when Enter key is down
' * it will look like this when Enter key is down
'
' {
' |
' }
'
' *
Private Sub RichTextBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles RichTextBox1.KeyDown
Dim sel As Integer = RichTextBox1.SelectionStart
If e.KeyCode = Keys.Enter Then
If isCurslyBracesKeyPressed = True Then
RichTextBox1.Text = RichTextBox1.Text.Insert(sel, vbLf & " " & vbLf)
e.Handled = True
RichTextBox1.SelectionStart = sel + " ".Length
isCurslyBracesKeyPressed = False
End If
End If
End Sub
End Class

9 Comments

Join the conversation! Your thoughts help the community grow.

Tridib Arjo6y ago
You are really mastermind. You should be top 1 in C Sharp Corner
Sushma M6y ago
How do i change colour for the brackets only
Pritam Zope10y ago
Thanks Kiranteja and Santhakumar
Santhakumar Munuswamy10y ago
Thanks for sharing
Kiranteja Jallepalli10y ago
Nice article..Pritam Zope,Welcome to C# Corner.
Pritam Zope10y ago
Thanks Raj
Raj Kumar10y ago
really good post
Pritam Zope10y ago
Thanks Sibeesh
Sibeesh Venu10y ago
Nice Share