Pass Value One Form to Another in WPF

Just Open your App.xaml file and nevigate on App.xaml.cs file.
 
Here is you define the variable like this: 
  1. public partial class App : Application  
  2. {  
  3.      public string Id { get; set; }  
  4.      public string Roll { get; set; }  
  5.      public string Center { get; set; }  
  6.      //...what ever which you want in property  
  7.   
  8.  } 
Then after defining property in App.xaml.cs  just access and set the value in property in another page like this. 
  1. public void Setvalue()// under the any function like this  
  2. {  
  3.    (App.Current as App).Id="Somevalue";    
  4.    (App.Current as App).Roll="Somevalue";    
  5.    (App.Current as App).Center="Somevalue";    
  6. }   
Then after setting the value of property access on another page like this. 
  1. public void Getvalue()// under the any function like this  
  2. {  
  3.    string id=(App.Current as App).Id;  
  4.    string id=(App.Current as App).Roll;  
  5.    string id=(App.Current as App).Center;  
  6. }