Check and uncheck all checkboxcolumns by another checkbox in C#.net

Hi Everyone....

How to check and uncheck Checkboxcolumns in datagridview by an another checkbox which is outside of that datagridview .

i have to fulfill three criteria which are explain below
1.If outside checkbox is checked then all datagridview checkboxes are checked and viceversa .

2.If all datagridview checkboxes are checked then outside checkbox will be also checked .

and
3. After clicking of outside checkbox all checkboxes are checked but if one of them is unchecked then ohers remain same but outside checkbox will be unchecked .

How can i do that ?

for first condition i have done these..

if (checkBox1.Checked == true)
 {
   for (int i = 0; i < datagridview1.RowCount; i++)
      {
        datagridview1[0, i].Value = true;
       }
  }

but for second ad third condition i can not get proper or exact solution....
please help..

Thank You

Tags: C#, .NET