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Jan 2 in C++

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nullptr in C++

1 Answer

Jan 2

At last, C++ has a keyword that designates a null pointer constant. nullptr replaces the bug-prone NULL macro and the literal 0 that have been used as null pointer substitutes for many years. nullptr is strongly-typed:

void f(int); //#1

void f(char *);//#2

//C++03

f(0); //which f is called?

//C++11

f(nullptr) //unambiguous, calls #2

nullptr is applicable to all pointer categories, including function pointers and pointers to members:

const char *pc=str.c_str(); //data pointers

if (pc!=nullptr)

cout<<pc<<endl;

int (A::*pmf)()=nullptr; //pointer to member function

void (*pmf)()=nullptr; //pointer to function

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