Yuan Yijun (bbbush) wrote,
Yuan Yijun

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const 和 typedef

今天学到的东西,就是 typedef 一个指针之后,再前置 const,const 的位置会是指针后面,也就是声明了常指针

// a.h
#pragma once
typedef const wchar_t* LPCWSTR;
const LPCWSTR a[] = { L"asdfasdf" };

// a.cpp
#include "a.h"

// b.cpp
#include "a.h"
int main(){ return 0;}

这里因为 LPCWSTR 没有被当做一个指针,因此按照规则 const 可以前置也可以后置。如果按照前置理解,const const wchar_t* 是没有意义的,因此在 gcc-c++ 和 m$-c++ 里面都按后置理解,也就是 const wchar_t* const。如果编译器知道 LPCWSTR 是一个指针,那么按照规则就不能修改 const 的位置了,可惜编译器不关心。


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