C + + learning Note NULL vs NULLPTR

Write in front

With the advent of the C++11 standard, C + + norms are increasingly rigorous, in reducing the two semantics of language, the C + + committee did a lot of efforts. As for those who have learned c++98 or 03 of the standard, think C + + sucks people, I just want to send four words, sit idle.

NULL vs nullptr

In the past, if we were to indicate that a pointer was empty, we would definitely say this:

int *p = NULL;

However, have you ever thought that this is problematic, such as the following code:

 #include <iostream> #include <string>using namespace std; void func (int* num) {cout <<  "This is the PTR function ..." << Endl;} void func (int num) {cout < <  "This is the normal function ..." << Endl; void Main (int argc, char** argv) { Func (NULL);}                

What will the program output?? I asked a lot of people, their unanimous answer is: Output This is the PTR function ... Ah, don't forget to bring a taunt. In fact, the output here is:

In fact, when the compiler interprets the program, NULL will be interpreted directly as 0, so the parameter here is not what everyone thought of NULL, the parameter has been secretly replaced by the compiler 0,0 is an integer ah, so the call is the second function. So some programmers also suggested that null be replaced by 0, which would reduce the difficulty of later maintenance. But how do I invoke the first function? There are many solutions on the Web (mostly written using previous standards).

C++11 the emergence of a complete solution to this problem, nullptr in c++11 is to represent the null pointer, can not be converted into a number (the specific bottom is how to achieve, we can look at the API, the author said not understand t_t), then we try again, see this time what is the result?

What, see the results.

C + + learning Note NULL vs NULLPTR