After creating a class called student i aslo include a constructor and destructor the implementation code is shown below.

student:: ~student(){;}

but i still have an error message as -
" return type specification for constructor invalid"
can any one help me figure whats wrong ??

Do you have any other constructors? (overloaded)
If not, post more code.

Implementation looks pretty fine. Post the declaration too.
BTW, the declaration should be

class student{
        //other stuff

[psychic debugging]
You probably forgot to terminate your class definition with a semicolon and the constructor definition immediately follows it. The following code should produce a similar error:

class foo {

foo::foo() {}

The error is saying that the constructor for foo is trying to use the type foo (specified by a class definition) as the return type for the constructor. However, a constructor doesn't have a return type, so the compiler issues a diagnostic.
[/psychic debugging]