String类的重写 C++

#include "String.h" #include <iostream.h> #include <string.h> String::String() { cout << "无参构造函数被调用" << endl; len = 0; m_data = new char[1]; m_data[0] = '\0'; } String::String(char *str) { cout << "带参构造函数被调用" << endl; len = strlen(str); m_data = new char[len + 1]; strcpy(m_data, str); } String::String(const String &other) { cout << "拷贝构造函数被调用" << endl; len = other.len; m_data = new char[len + 1]; strcpy(m_data, other.m_data); } String & String::operator =(const String &other) //赋值函数 { cout << "重载 = 函数被调用" << endl; if(this == &other) { return *this; } delete [] m_data; len = other.len; m_data = new char [len + 1]; strcpy(m_data, other.m_data); return *this; } String::~String() { cout << "析构函数被调用" << endl; delete [] m_data; } void String::display() { cout << "m_data= " << m_data << " len = " << len << endl; } String operator + (const String &s1, const String &s2) { cout << "重载 + 函数被调用" << endl; String temp; delete temp.m_data; temp.len = s1.len + s2.len; temp.m_data = new char [temp.len + 1]; strcpy(temp.m_data, s1.m_data); strcat(temp.m_data, s2.m_data); return temp; }