# CodeGuru Technical FAQs > CodeGuru Individual FAQs >  C++ General: What is the 'this' pointer?

## cilu

*Q:* What is the 'this' pointer?

*A:* It is a misbelief that the *'this'* pointer is a hidden member of a class or struct. It is a hidden parameter of non-static member functions. When you declare a function the compiler adds an extra parameter to function's prototype. The type of the parameter depends on how the function is declared. According to C++ standard, 9.3.2.1:



> In the body of a nonstatic member function, the keyword this is a non-lvalue expression whose value is the address of the object for which the function is called. The type of this in a member function of a class X is X*. If the member function is declared const, the type of this is const X*, if the member function is declared volatile, the type of this is volatile X*, and if the member function is declared const volatile, the type of this is const volatile X*.


For instance 


```
class T
{
public:
  void foo(int a);
  int goo() const;
};
```

is actually:


```
class T
{
public:
  void foo(T* this , int a);
  int goo(const T* this) const;
};
```

Static member functions, which dont have class scope, do not have this extra parameter. One consequence is that you cannot use a non-static member function as a thread function even if it has the correct prototype


```
UINT ThreadFunction(LPVOID param);
```

because that in fact the prototype (when non-static) is


```
UINT ThreadFunction(T* this, LPVOID param);
```

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## exterminator

There are a few more peculiarities of the this pointer:
It is impossible to take the address of the this pointer.It is impossible to assign anything to the this pointer. (i.e. its not an l-value).

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