我不明白的是為什么構造函數參數是引用類型的會如此依賴參數是指針類型的，難道是因為參數是指針類型的構造函數計算了指針char* str的長度嗎？String::String(const char* str){len = strlen(str);this->str = new char[len + 1];strcpy(this->str, str);num_strings++;}String::String(const String& s){this->len = s.len;this->str = new char[this->len + 1];strcpy(this->str, s.str);num_strings++;}int String::length() const{return len;}String& String::operator=(char* s){delete[] this->str;len = strlen(s);str = new char[len + 1];strcpy(this->str, s);return *this;}String& String::operator=(String& s){if (str) {//如果str類成員存在delete[]str;//釋放它str = NULL;}len = s.len;str = new char[len + 1];strcpy(str, s.str);return *this;}—————————————————————————————————————下面是類：#ifndef STRING_H_#define STRING_H_#include<iostream>#include<cstring>using std::cout;using std::cin;using std::endl;namespace STRING {class String{public://構造函數析構函數和其他方法String();~String();String(const char* str);String(const String& s);int length()const;//返回len的方法//重載運算符方法String& operator=(char* s);String& operator=(String& s);char& operator[](int i);const char& operator[](int i)const;//友元函數 重載運算符friend bool operator<(const String& t1, const String& t2);friend bool operator>(const String& t1, const String& t2);friend bool operator==(const String& t1, const String& t2);friend std::ostream& operator<<(std::ostream& os, String& t);friend std::istream& operator>>(std::istream& is, String& t);//靜態方法 返回num_string值的方法static int HowMany();private:char* str;int len;static int num_strings;static const int CINLIM = 80;};}#endif // !STRING_H_