const qualifier 释义 : const修饰符

• const
• constexpr
• const_cast

通过将变量的类型定义为const，可以使变量不可变:

const int bufSize = 512; // input buffer size
bufSize = 512; // error: attempt to write to const object

Because we can’t change the value of a const object after we create it, it must be
initialized.

const int i = get_size(); // ok: initialized at run time
const int j = 42; // ok: initialized at compile time
const int k; // error: k is uninitialized const

推翻自己旧的错误知识，非const入参不能接收const入参，const入参可以接收const和非const入参

#include <iostream>using namespace std;class B {
public:B(int d) :data_(d) {}int data() {return this->data_;}
private:int data_;
};class A {
public:void func(B a) {std::cout << a.data() << std::endl;}void work() {const B b(23);func(b);}
};
int main()
{int i = 42;const int ci = i;int j = ci;A a;a.work();return 0;
}