串（string）类的简单实现

来源：互联网发布：福岛核事故知乎编辑：程序博客网时间：2024/06/13 20:55

串（String）又称字符串，是一种特殊的线性表，表中的元素是单个字符，串是由n个字符组成的有限序列。

S="c1c2c3c4...cn"............(n>=0)

本文实现了串的初始化，串长度的计算，求子串，插入、删除、加法、找位置以及串的输出等函数。

String.h

#ifndef STRING_H_#define STRING_H_#include <iostream>class String{private:char *str;int size;public:String();String(char *chx);~String();void Creat();void Display();int Length() const;String SubString(int pos, int num);void Insert(String s, int pos);void Delete(int pos, int num);String operator+(String s);int Find(String s, int pos);friend std::ostream &operator <<(std::ostream &os, String str);};#endif

Str.cpp

#include "StdAfx.h"#include "String.h"#include <iostream>using std::cout;using std::endl;using std::cin;String::String(){str=new char;if(!str){cout<<"分配不成功"<<endl;}size=0;str[0]='\0';}String::String(char *chx){size=strlen(chx);str=new char[size];strcpy(str,chx);}String::~String(){}void String::Creat(){char *ch;ch=new char;cout<<"Input string: ";cin>>ch;size=strlen(ch);str=new char[size+1];strcpy(str,ch);}void String::Display(){cout<<"字符串为："<<str<<endl;}int String::Length() const{return size;}//取其中一部分，从pos开始，去num个字符String String::SubString(int pos, int num){String tp;if(pos<0 || pos>size || num<=0){cout<<"超出范围"<<endl;return tp;}int left=size-pos;if(num>left){num=left;}delete []tp.str;//由于num的值可能改变，故对申明的字符串先释放再重新申明tp.str=new char[num+1];for(int i=0, j=pos-1; i<num; i++,j++){tp.str[i]=str[j];}tp.str[num]='\0';tp.size=num;return tp;}void String::Insert(String s, int pos){if(pos<0 || pos>size){cout<<"超出范围"<<endl;}else{int size0=s.size+size;for(int i=size; i>=pos; --i){str[s.size+i]=str[i];}for(int i=pos; i<s.size+pos; i++){str[i]=s.str[i-pos];}size=size0;str[size]='\0';}}void String::Delete(int pos, int num){if(pos<0 || pos>size){cout<<"超出范围"<<endl;}else{int left=size-pos;if(left<num)size=pos;else{for(int i=pos; i<size-num; i++){str[i]=str[num+i];}size=size-num;}str[size]='\0';}}String String::operator+(String s){strcat(str,s.str);size=size+s.size;str[size]='\0';return *this;}//朴素模式匹配,该算法思路直观简明，但时间复杂度比较大。int String::Find(String s, int pos){int flag=0;--pos;//第pos字符位置在pos-1上for(int i=pos,j=0; i<size; i++){if(str[i]==s.str[j]){for(int t=0; t<s.size; t++){if(str[i+t]==s.str[t]){++flag;}}if(flag==s.size){return i+1;}}flag=0;}return -1;}std::ostream &operator <<(std::ostream &os, String str){cout<<str.str;return os;}

string.cpp

// string.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include "String.h"#include <iostream>using namespace std;int _tmain(int argc, _TCHAR* argv[]){String str1;str1.Creat();cout<<"字符串为："<<str1<<endl;str1.Display();cout<<"字符串的长度为："<<str1.Length()<<endl;/////String str(" is a good person!");cout<<"字符串为："<<str<<endl;str.Display();cout<<"字符串的长度为："<<str.Length()<<endl;/////str=str1+str;cout<<"字符串为："<<str<<endl;str.Display();cout<<"字符串的长度为："<<str.Length()<<endl;str.Insert("not ",13);cout<<"字符串为："<<str<<endl;/////String substr=str.SubString(13,10);cout<<"字符串为："<<substr<<endl;/////str.Delete(13,4);cout<<"字符串为："<<str<<endl;char *findstr="person";int pos=str.Find(findstr,1);cout<<"字符串\""<<findstr<<"\"的起始位置为：";if(pos==-1){cout<<"不存在！"<<endl;}else{cout<<pos<<endl;}system("pause");return 0;}

结果：

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