Impersonate user SystemAdmin Sharepoint Programmatically

Dim tempsite As SPSite = New SPSite("http://localhost/a")
Dim usertoken As SPUserToken = tempsite.SystemAccount.UserToken()

Using site As SPSite = New SPSite("http://localhost/a", usertoken)
Using oWebsite As SPWeb = site.OpenWeb()

'bla bla bla your code inside here

Check user permission Sharepoint programmatically

Public Function checkUserPermissionSP() As Boolean
Using site As SPSite = New SPSite("http://localhost/yoursite")

Using Web As SPWeb = site.OpenWeb()
If Web.DoesUserHavePermissions(SPBasePermissions.EnumeratePermissions) Then
Dim permissionToCheck As SPBasePermissions = SPBasePermissions.ManageLists
Console.WriteLine("The following users have {0} permission:", permissionToCheck)
Dim users As SPUserCollection = Web.Users
Dim user As SPUser
For Each user In users
Dim login As String = user.LoginName
If Web.DoesUserHavePermissions(login, permissionToCheck) Then
Console.WriteLine(login)
Return True
Else
Return False
End If
Next
Else : Return False
End If
End Using
End Using

End Function