串

MyString.h

const int MAXSIZE=100;

class CMyString
{
public:
	CMyString(const CMyString& copy);
	CMyString(const char *init);
	CMyString();
	~CMyString(){
		delete[] m_pstr;
	}
	int Length() const{
		return m_ncurlen;
	}
	int Find(CMyString part) const;
	char* GetBuffer() const;

public:
	CMyString& operator()(int pos,int len);
	bool operator==(const CMyString cmp_str) const;
	bool operator!=(const CMyString cmp_str) const;
	bool operator<(const CMyString cmp_str) const;
	bool operator>(const CMyString cmp_str) const;
	bool operator!() const{
		return m_ncurlen==0;
	}
	CMyString& operator=(const CMyString &copy);
	CMyString& operator+=(const CMyString &add);
	char& operator[](int i);
	friend ostream& operator<<(ostream& ,CMyString&);
	friend istream& operator>>(istream& ,CMyString&);
private:
	void Next();

private:
	int m_ncurlen;
	char *m_pstr;
	int *m_pnext;
};

MyString.cpp

#include <iostream>
#include <cstring>

using namespace std;

#include "MyString.h"



CMyString::CMyString(){			//create empty string
	m_pstr=new char[MAXSIZE+1];
	if(!m_pstr){
		cerr<<"Allocation Error"<<endl;
		exit(1);
	}
	this->m_ncurlen=0;
	m_pstr[0]='\0';
}

CMyString::CMyString(const char *init){		//initialize the string with char*
	m_pstr=new char[MAXSIZE+1];
	if(!m_pstr){
		cerr<<"Allocation Error"<<endl;
		exit(1);
	}
	this->m_ncurlen=strlen(init);
	strcpy(m_pstr,init);
}

CMyString::CMyString(const CMyString &copy){	//initialize the string with string
	m_pstr=new char[MAXSIZE+1];
	if(!m_pstr){
		cerr<<"Allocation Error"<<endl;
		exit(1);
	}
	this->m_ncurlen=copy.m_ncurlen;
	strcpy(m_pstr,copy.m_pstr);
}

int CMyString::Find(CMyString part) const{		//string match :KMP
	int posP=0,posT=0;
	int lengthP=part.m_ncurlen,lengthT=this->m_ncurlen;

	part.Next();
	while(posP<lengthP&&posT<lengthT){
		if(part.m_pstr[posP]==this->m_pstr[posT]){
			posP++;
			posT++;
		}
		else{
			if(posP==0){
				posT++;
			}
			else{
				posP=part.m_pnext[posP-1];
			}
		}
	}
	delete[] part.m_pnext;
	if(posP<lengthP){
		return 0;
	}
	else{
		return 1;
	}
}

void CMyString::Next(){			//get the next char for matching : KMP
	int length=this->m_ncurlen;
	this->m_pnext=new int[length];
	this->m_pnext[0]=0;
	for(int i=1;i<length;i++){
		int j=this->m_pnext[i-1];
		while(*(this->m_pstr+i)!=*(this->m_pstr+j)&&j>0){
			j=this->m_pnext[j-1];
		}
		if(*(this->m_pstr+i)==*(this->m_pstr+j)){
			this->m_pnext[i]=j+1;
		}
		else{
			this->m_pnext[i]=0;
		}
	}
//	for(int i=0;i<length;i++)
//		cout<<i<<":\t"<<m_pnext[i]<<endl;
}

char *CMyString::GetBuffer() const{		//get the char* from string
	return this->m_pstr;
}

CMyString& CMyString::operator()(int pos, int len){		//get len char with the begining of pos
	CMyString *temp=new CMyString;
	if(pos<0||pos+len-1>MAXSIZE||len<0){
		temp->m_ncurlen=0;
		temp->m_pstr[0]='\0';
	}
	else{
		if(pos+len-1>=m_ncurlen){
			len=m_ncurlen-pos;
		}
		temp->m_ncurlen=len;
		for(int i=0,j=pos;i<len;i++,j++){
			temp->m_pstr[i]=m_pstr[j];
		}
		temp->m_pstr[len]='\0';
	}
	return *temp;
}

bool CMyString::operator==(const CMyString cmp_str) const{
	if(this->m_ncurlen!=cmp_str.m_ncurlen){
		return 0;
	}
	for(int i=0;i<this->m_ncurlen;i++){
		if(this->m_pstr[i]!=cmp_str.m_pstr[i])
			return 0;
	}
	return 1;
}
bool CMyString::operator!=(const CMyString cmp_str) const{
	if(*this==cmp_str)
		return 0;
	return 1;
}
bool CMyString::operator<(const CMyString cmp_str) const{
	if(this->m_ncurlen!=cmp_str.m_ncurlen){
		return this->m_ncurlen<cmp_str.m_ncurlen;
	}
	for(int i=0;i<this->m_ncurlen;i++){
		if(this->m_pstr[i]!=cmp_str.m_pstr[i]){
			return this->m_pnext[i]<cmp_str.m_pnext[i];
		}
	}
	return 0;
}
bool CMyString::operator>(const CMyString cmp_str) const{
	if(*this<cmp_str||*this==cmp_str){
		return 0;
	}
	return 1;
}
CMyString& CMyString::operator=(const CMyString &copy){		//赋值操作
	delete[] this->m_pstr;
	this->m_pstr=new char[copy.m_ncurlen+1];
	strcpy
		(this->m_pstr,copy.m_pstr);
	return *this;
}
CMyString& CMyString::operator+=(const CMyString &add){		//字符串追加
	int length=this->m_ncurlen+add.m_ncurlen;
	int n=this->m_ncurlen;
	CMyString temp(*this);
	delete[] this->m_pstr;
	this->m_pstr=new char[length+1];
	for(int i=0;i<n;i++){
		this->m_pstr[i]=temp[i];
	}
	for(int i=n;i<length;i++){
		this->m_pstr[i]=add.m_pstr[i-n];
	}
	this->m_pstr[length]='\0';
	return *this;
}
char& CMyString::operator[](int i){		//取元素
	if(i<0||i>=this->m_ncurlen){
		cout<<"out of boundary!"<<endl;
		exit(1);
	}
	return this->m_pstr[i];
}

ostream& operator<<(ostream& os,CMyString& str){
	os<<str.m_pstr;
	return os;
}

istream& operator>>(istream& is,CMyString& str){
	is>>str.m_pstr;
	return is;
}

test.cpp

#include <iostream>

using namespace std;

#include "MyString.h"

int main(){
	CMyString test1("babc");
	CMyString test2("abababcdefb");
	cout<<test2.Find(test1)<<endl;
	cout<<test2(2,3)<<endl;

	if(test1<test2){
		cout<<test1<<"<"<<test2<<endl;
	}
	else{
		if(test1==test2){
			cout<<test1<<"=="<<test2<<endl;
		}
		else{
			if(test1>test2){
				cout<<test1<<">"<<test2<<endl;
			}
		}
	}

	int length=test2.Length();
	for(int i=0;i<length;i++){
		cout<<test2[i];
	}
	cout<<endl;

	test1+=test2;
	cout<<test1<<endl;

	test1=test2;
	cout<<test1<<endl;

	return 0;
}