要注意字符串是否为空
代码实现：
#include <iostream> using namespace std; #include <string.h> class CString { public: CString(char* p = "")//构造函数 { mstr = new char[strlen(p) + 1](); strcpy(mstr, p); } CString(const CString& rhs)//拷贝构造函数 { mstr = new char[strlen(rhs.mstr) + 1](); strcpy(mstr, rhs.mstr); } ~CString()//析构函数 { delete mstr; mstr = NULL; } CString& operator=(const CString& rhs)//赋值运算符的重载函数 { if (this != &rhs) { delete mstr; mstr = new char[strlen(rhs.mstr) + 1]; strcpy(mstr, rhs.mstr); } return *this; } bool operator !=(const CString& rhs)//重载!= { return strcmp(mstr, rhs.mstr) != 0; } bool operator ==(const CString& rhs)//重载== { return !(*this != rhs); } private: char* mstr; friend istream& operator >>(istream&, CString&);//重载输入流运算符 friend const CString operator+(const CString&, const CString&);//重载+ friend ostream& operator<<(ostream&, const CString&);//重载输出流运算符 }; //类外实现重载输入流运算符 istream& operator >>(istream& in, CString& rhs) { char *p = new char[100](); in >> p; int i = 0; if (p[99] == '0') { i = strlen(p); } else { i = 100; } delete rhs.mstr; rhs.mstr = new char[i + 1](); strcpy(rhs.mstr, p); return in; } //类外实现重载+ const CString operator+(const CString& lhs, const CString& rhs) { char* tmp = new char[strlen(lhs.mstr) + strlen(rhs.mstr) + 1](); strcat(tmp, lhs.mstr); strcat(tmp, rhs.mstr); return CString(tmp); } //类外实现重载输出流运算符 ostream& operator<<(ostream& out, const CString& rhs) { out << rhs.mstr << " "; return out; } int main() { CString str1; CString str2("hello"); CString str3(str2); cout << "str1:"; cin >> str1; str3 = "hello"; str3 = str3 + "world"; cout << "str2:" << str2 << endl; cout <<"str3:" << str3 << endl; return 0; }string类是C++中很重要的类 一定要掌握 面试的时候会问到
运行结果：
