第八周项目五----string类的扩充

/** 程序的版权和版本声明部分* Copyright (c)2013, 烟台大学计算机学院学生* All rightsreserved.* 文件名称： object.cpp* 作者：赵晓晨* 完成日期： 2013年04月21日* 版本号： v1.0* 输入描述：无* 问题描述：无* 程序输出：无*/#include<iostream>#include <Cstring>using namespace std;class String{public:    String( );  //    String(const char *s);    String(String &str);    ~String();    void display( );    //友元函数做重载函数    friend String operator + (String &s1,String &s2 );    friend String operator - (String &s1,String &s2 );    friend String operator * (String &s1,int n );    friend String operator / (String &s1,String &s2 );private:    char *p;    int len;};//类string的定义String::String(){    len = 0;    p = NULL;}String::String(const char *s){    len = strlen(s);    p = new char[len+1];    strcpy(p,s);}String::String(String &str){    len = str.len;    p = new char[len+1];    strcpy(p,str.p);}String::~String(){    if(!p)        delete []p;}void String::display( ){    cout<<p;}//友元函数做重载函数的形式String operator + (String &s1, String &s2 ){    String s;    s.len = s1.len+s2.len;    s.p = new char(s.len+1);    strcpy(s.p,s1.p);    strcat(s.p,s2.p);    return s;}String operator - (String &s1, String &s2 ){    String s;    char *c1=new char[s1.len+1];    strcpy(c1,s1.p);    int i=s1.len-1;    while(i>=0&&c1[i]==' ') --i;    c1[i+1]='\0';    char *c2=new char[s2.len+1];    strcpy(c2,s2.p);    i=0;    while(i<s2.len&&c2[i]==' ') ++i;    int j=0;    while(i<s2.len&&c2[i]!='\0')    {        c2[j]=c2[i];        ++i;        ++j;    }    c2[j+1]='\0';    s.len = strlen(c1)+strlen(c2);    s.p = new char(s.len+1);    strcpy(s.p,c1);    strcat(s.p,c2);    delete c1;    delete c2;    return s;}//main函数进行测试int main( ){    String string1(" 晓晨"),string2(" 加油 ");    string1.display();    cout<<endl;    String string3;    string3 = string1 + string2;    string3.display();    return 0;}

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