C++ string類的簡單實現__C++

#include <string.h>#include <iostream>using namespace std;class String{public:String(const char* str = NULL);String(const String &other);String & operator=(const String &other);~String();protected:private:char* m_data;};String::String(const char *str ){if (str == NULL){m_data = new char[1];*m_data = '\0';} else{m_data = new char[strlen(str)+1];strcpy(m_data,str);}}String::~String(){delete m_data;}String::String(const String &other){int length = strlen(other.m_data);m_data = new char[length+1];strcpy(m_data,other.m_data);}String & String::operator=(const String &other){if (this == &other){return *this;}delete m_data;int len = strlen(other.m_data);m_data = new char[len+1];strcpy(m_data,other.m_data);return *this;}void test(){String s1 = "hello";  //調用建構函式String s2 ;           //調用建構函式s2 = s1;              //調用賦值建構函式String s3(s1);        //調用拷貝建構函式}                         //一次調用解構函式int main(){test();return 0;}