C++进阶：新人易入的那些坑 --1.常量、常指针和指针常量

声明：以下内容B站/Youtube学习笔记,https://www.youtube.com/user/BoQianTheProgrammer/ Advanced C++.

 /*
 why use const
 a)Guards against inadvertent write to the variable
 b)Self documenting
 c)Enables compiler to do more optimization,making code tighter,faster
 d)const means the variable can be put in ROM
 */
 //const
 // A compile time constraint that an object can not  be modified

 int main()
 {
     const int i = ;
     //i = 7; wrong
     //如何修改i的值呢？
     const_cast<int&>(i) = ;

     int j;
     static_cast<const int&>(j) = ;//wrong，此时j被转成const

     const int *p1 = &i;//data is const,pointer is not
     p1++;
     int * const p2;//pointer is const,data is not
     const int* const p3;//data and pointer are both const

     int const *p4 = &i;
     const int *p4 = &i;
     //If const is on the left of *,data is const
     //If const is on the right of *,pointer is const
 }