c++运算符重载总结

来源：互联网发布：python安装不了编辑：程序博客网时间：2024/05/10 15:06

今天学了运算符的重载，对于c++，相比C语言而言语法又多且杂，难背又难记，最近真有点懈怠......还是要加油

#ifndef _STRING_H_#define _STRING_H_#include <iostream>using namespace std;class String{public:    //static int MAX_LEN;    //friend class StringTool;    //friend void print(const String &s1);    String();    String(char *str);    ~String();    String(const String& other);    void myStrcat();    void Display() const;    void setMAXLEN(int maxLen);    int getMAXLEN();    String& operator=(const String& other);    String& operator=(char *str);    char& operator[](unsigned int index);    const char& operator[](unsigned int index) const;    String& operator+=(const String &s);        friend String operator+(const String& s1, const String& s2);    friend ostream& operator<<(ostream &out, const String &s);    friend istream& operator>>(istream &in,String& s);    operator char *();private:    char *str_;    static const int MAX_LEN = 1024;    //String(const String& other);//绂佹鎷疯礉};#endif

#include <iostream>#include <string.h>#include "String.h"using namespace std;//int String::MAX_LEN = 1024;String::String(){    str_ = new char('\0');    cout <<  "default constrcutor String" << endl;}String::String(char *str){    cout << "construct String" << endl;//str_ = str;    int len = strlen(str) + 1;    str_ = new char[len];    memset(str_,0,len);    strcpy(str_,str);}String::String(const String& other){    int len = strlen(other.str_) + 1;    str_ =  new char[len];    memset(str_,0,len);    strcpy(str_,other.str_);}String::~String(){    cout << "destroy String" << endl;      delete [] str_;}String::operator char*(){    return str_;}String& String::operator=(const String& other){    if(this == &other)    {        return *this;    }    int len = strlen(other.str_) + 1;        delete [] str_;    str_ = new char[len];    memset(str_,0,len);    strcpy(str_,other.str_);    return *this;}String& String::operator=(char *str){    cout << "operator char *str" << endl;        int len = strlen(str) + 1;        delete [] str_;    str_ = new char[len];    memset(str_,0,len);    strcpy(str_,str);    return *this;}char& String::operator[](unsigned int index){    cout << "no const []" << endl;    return const_cast<char&>(static_cast<const String&>(*this)[index]);}const char& String::operator[](unsigned int index) const{    cout << "const []" << endl;        return str_[index];}String operator+(const String& s1, const String& s2){    /*    int len = strlen(s1.str_) + strlen(s2.str_) + 1;    char *newptr= new char[len];    memset(newptr,0,len);    strcpy(newptr,s1.str_);    strcat(newptr,s2.str_);    String temp(newptr);    */        String temp(s1);    temp += s2;    return temp;}String& String::operator+=(const String &s){    int len = strlen(str_) + strlen(s.str_) + 1;       char *newptr = new char[len];    strcpy(newptr,str_);    strcat(newptr,s.str_);    delete [] str_;    str_ = new char[len];    strcpy(str_,newptr);    return *this;}ostream& operator<<(ostream &out, const String& s){    out << s.str_;    return out;}istream& operator>>(istream &in, String& s){    char buffer[1024];    in >> buffer;    int len = strlen(buffer) + 1;    delete [] s.str_;    s.str_ = new char[len];    strcpy(s.str_,buffer);    return in;}void String::Display() const{    cout << str_ << endl;}void String::setMAXLEN(int maxLen){}int String::getMAXLEN(){    return MAX_LEN;}

#include <iostream>#include "String.h"#include "Stringtool.h"using namespace std;int main(){   #if 0    String s1;    s1 = "hello";        cout << s1[1] << endl;        s1[1] = 'E';        s1.Display();    String s2("world");    cout << s2[1] << endl;    //s[2] = 'L';    String s3("kkk");    //s3 = s1 + s2;    s3+=s1;//s3 = s3 + s1;    s3.Display();    #endif        String s("hello world");    cout << s << endl;        cin >> s;    cout << s << endl;        char *ptr = static_cast<char *>(s);         cout << ptr << endl;    return 0;}

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