Tutorial :In c++ what does a tilde “~” before a function name signify?


 template <class T>   class Stack   {   public:      Stack(int = 10) ;       ~Stack() { delete [] stackPtr ; }  //<--- What does the "~" signify?      int push(const T&);       int pop(T&) ;        int isEmpty()const { return top == -1 ; }       int isFull() const { return top == size - 1 ; }    private:      int size ;        int top ;        T* stackPtr ;     } ;  


It's the destructor, it destroys the instance, frees up memory, etc. etc.

Here's a description from ibm.com:

Destructors are usually used to deallocate memory and do other cleanup for a class object and its class members when the object is destroyed. A destructor is called for a class object when that object passes out of scope or is explicitly deleted.

See https://www.ibm.com/support/knowledgecenter/SSB27U_5.4.0/com.ibm.zos.r9.cbclx01/cplr380.htm


As others have noted, in the instance you are asking about it is the destructor for class Stack.

But taking your question exactly as it appears in the title:

In c++ what does a tilde “~” before a function name signify?

there is another situation. In any context except immediately before the name of a class (which is the destructor context), ~ is the one's complement (or bitwise not) operator. To be sure it does not come up very often, but you can imagine a case like

if (~getMask()) { ...  

which looks similar, but has a very different meaning.


It's a destructor. The function is guaranteed to be called when the object goes out of scope.


This is a destructor. It's called when the object is destroyed (out of life scope or deleted).

To be clear, you have to use ~NameOfTheClass like for the constructor, other names are invalid.


It's the destructor. This method is called when the instance of your class is destroyed:

Stack<int> *stack= new Stack<int>;  //do something  delete stack; //<- destructor is called here;  


That would be the destructor(freeing up any dynamic memory)

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