C++自学笔记_重载运算符_《C++ Primer》

#include <iostream>
#include <stdexcept>

using namespace std;

class CheckedPtr{
public:
    CheckedPtr(int *b,int *e,int *c):
        beg(b),end(e),curr(c){ }
    CheckedPtr(const CheckedPtr &obj):   //复制构造函数
        beg(obj.beg),end(obj.end),curr(obj.curr){ }
    CheckedPtr& operator++();            //prefix operators
    CheckedPtr& operator--();            //prefix operators
    CheckedPtr& operator++(int);         //postfix operators
    CheckedPtr& operator--(int);         //postfix operators
    int& operator[](const size_t);       //重载下标运算符
    const int& operator[](const size_t) const;
    int& operator*();                    //重载解解引用操作符
    const int& operator*() const;
    friend bool operator==(const CheckedPtr&,const CheckedPtr&);        //重载=运算符
    friend bool operator!=(const CheckedPtr&,const CheckedPtr&);        //重载!=运算符
    friend bool operator<(const CheckedPtr&,const CheckedPtr&);         //重载<运算符
    friend bool operator>(const CheckedPtr&,const CheckedPtr&);         //重载>运算符
    friend bool operator<=(const CheckedPtr&,const CheckedPtr&);        //重载<=运算符
    friend bool operator>=(const CheckedPtr&,const CheckedPtr&);        //重载>=运算符
    friend CheckedPtr operator+(const CheckedPtr&,const size_t);        //重载+运算符
    friend CheckedPtr operator-(const CheckedPtr&,const size_t);        //重载-运算符
private:
    int *beg;
    int *end;
    int *curr;
};

CheckedPtr& CheckedPtr::operator++(){
    if(curr==end)
        throw out_of_range("increment past the end of CheckedPtr");
    ++curr;
    return *this;
}

CheckedPtr& CheckedPtr::operator--(){
    if(curr==beg)
        throw out_of_range("decrement past the beginning of CheckedPtr");
    --curr;
    return *this;
}

CheckedPtr& CheckedPtr::operator++(int){
    CheckedPtr ret(*this);
    ++*this;
    return ret;
}

CheckedPtr& CheckedPtr::operator--(int){
    CheckedPtr ret(*this);
    --*this;
    return ret;
}

    /*习题14.23*/
int& CheckedPtr::operator[](const size_t index){
    if(index+beg>=end||index+beg<beg)        //此处的end指向数组最后一个元素的下一个位置，所以有等号
        throw out_of_range("invalid index");
    return *(beg+index);
}

const int& CheckedPtr::operator[](const size_t index) const{
    if(index+beg>=end||index+beg<beg)
        throw out_of_range("invalid index");
    return *(beg+index);
}

int& CheckedPtr::operator*(){
    if(curr==end)
        throw out_of_range("invalid current pointer*");
    return *curr;
}

const int& CheckedPtr::operator*() const{
    if(curr==end)
        throw out_of_range("invalid current pointer*");
    return *curr;
}

    /*习题14.25*/
bool operator==(const CheckedPtr &obj1,const CheckedPtr &obj2){
    return obj1.beg==obj2.beg&&obj1.end==obj2.end&&obj1.curr==obj2.curr;
}

bool operator!=(const CheckedPtr &obj1,CheckedPtr &obj2){
    return !(obj1==obj2);
}

bool operator<(const CheckedPtr &obj1,const CheckedPtr &obj2){
    return obj1.beg==obj2.beg&&obj1.end==obj2.end&&obj1.curr<obj2.curr;
}

bool operator>(const CheckedPtr &obj1,const CheckedPtr &obj2){
    return obj1.beg==obj2.beg&&obj1.end==obj2.end&&obj1.curr>obj2.curr;
}

bool operator<=(const CheckedPtr &obj1,const CheckedPtr &obj2){
    return !(obj1>obj2);
}

bool operator>=(const CheckedPtr &obj1,const CheckedPtr &obj2){
    return !(obj1<obj2);
}

    /*习题14.26*/
CheckedPtr operator+(const CheckedPtr &obj,const size_t n){
    CheckedPtr tmp(obj);
    if(obj.curr+n>=obj.end)
        throw out_of_range("too large n");
    tmp.curr+=n;
    return tmp;
}

CheckedPtr operator-(const CheckedPtr &obj,const size_t n){
    CheckedPtr tmp(obj);
    if(obj.curr-n<obj.beg)
        throw out_of_range("too large n");
    return tmp;
}