写一个能处理字符串的类。
#include <iostream>#include <Cstring>using namespace std;class String{public:String( );//默认构造函数String(const char *s);String(String &str);//构造函数~String();void display( );friend String operator + (String &s1,String &s2 );friend String operator – (String &s1,String &s2 );private:char *p;int len;//字符型指针，用于指向字符串};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;if(p!=NULL) delete []p; //当发生在赋值等情形时，原对象可能已经存在，，需释放原有空间p = new char[len+1];strcpy(p,str.p);}String::~String(){if(!p) delete []p;}void String::display( )//输出p所指向的字符串{cout<<p<<endl;}String operator + (String &s1, String &s2 ){String s;s.len = s1.len+s2.len;s.p = new char[s.len+1]; //原误写char(s.len+1)strcpy(s.p,s1.p);strcat(s.p,s2.p);return s;}String operator – (String &s1, String &s2 ){String s;//c1为截去尾部空格的字符串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';//c2为去除前导空格的字符串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]='\0';//将这两部分接起来s.len = strlen(c1)+strlen(c2);s.p = new char[s.len+1];//原误写char(s.len+1)strcpy(s.p,c1);strcat(s.p,c2);delete c1;delete c2;return s;}int main( ){String string1("Aloha "), string2(" Mayuko");string1.display();string2.display();String string3;string3 = string1 + string2;string3.display();string3 = string1 – string2;string3.display();return 0;}
运行结果：
@ Mayuko
一个积极奋进的目标，一种矢志不渝的追求。
