sstring.h

数据结构常用算法——向量应用。希望能给读者朋友带来帮助。

#include "iostream.h"
#include "string.h"
class String{
public:
	String();
	String(char);
	String(unsigned);
	String(const char *);
	String(const String &);
	~String();
	char * pointer(void);
	unsigned StrLength(void);
	String & operator = (const String & );
	String & operator = (const char *);
	String & operator += (const String & );
	char & operator[] (unsigned);
	String operator ( )(unsigned, unsigned) const;
	friend istream & operator >> (istream &,String &);
	friend ostream & operator << (ostream &,const String &);
	const String operator + (const String &) const;
	int operator == (const String &) const;
	int compare(const String & str) const;
private:
	unsigned buflen;
	char * buffer;
};

String::String( ){
    buflen = 1;
    buffer = new char [buflen];
    buffer[0] = '\0';
}

String::String(char c){
    buflen = 2;
    buffer = new char [buflen];
    buffer[0] = c;
    buffer[1] ='\0';
}

String::String(const char *s){
    buflen = strlen(s) + 1;
    buffer = new char [buflen];
    strcpy(buffer,s);
}

String::String(unsigned n){
    buflen = n + 1;
    buffer = new char [buflen];
    for (unsigned i=0;i<buflen;i++)
        buffer[i]='\0';
}

String::String(const String & str){
    buflen = str.buflen;
    buffer = new char [buflen];
    strcpy(buffer,str.buffer);
}

String::~String(void){
    delete [] buffer;
}

char* String::pointer(void){
	return buffer;
}

unsigned String::StrLength(void){
	return buflen-1;
}

String & String::operator = (const String & str){
    if (str.buflen != buflen){
        buflen = str.buflen;
        delete [] buffer;
        buffer = new char [buflen];
    }
	strcpy(buffer, str.buffer);
    return *this;
}

String & String::operator = (const char * s){
    unsigned slen = strlen(s) + 1;
    if (slen != buflen) {
        delete [] buffer;
        buffer = new char [slen];
        buflen = slen;
    }
    strcpy(buffer,s);
    return *this;
}

String & String::operator+=(const String & str){
    char * tempstr;
    unsigned len;
    len = buflen + str.buflen-1;
    tempstr = new char [len];
    strcpy(tempstr,buffer);
	strcat(tempstr,str.buffer);
    delete [] buffer;
    buffer = tempstr;
    buflen = len;
    return *this;
}

char & String::operator [] (unsigned n){
    return buffer[n];
}

String String::operator( )(unsigned start, unsigned len) const{
    unsigned tlen;
	if (start >= buflen)
        return "";
    if (start-1+len >= buflen)
        tlen = buflen-start;
    else
        tlen = len;
    char * temp;
	temp=new char [tlen+1];
    for(unsigned i=0;i < tlen;i++)
        temp[i] = buffer[start+i-1];
	temp[i]='\0';
    return temp;
}

istream & operator >> (istream & in,String & str){
    char inbuffer[1000]={'\0'};
	cout<<"请输入字符串：";
//    if (in >> inbuffer)
//        str=inbuffer;
//    else
//		str="";
	in.getline(inbuffer,1000,'\n');
	str=inbuffer;
    return in;
}

ostream & operator << (ostream & out,const String & str){
	out << str.buffer;
    return out;
}

const String String::operator + (const String& str) const{
	String temp;
	temp.buflen=buflen+str.buflen-1;
	temp.buffer=new char [temp.buflen];
	strcpy(temp.buffer,buffer);
	strcat(temp.buffer,str.buffer);
	return temp;
}

int String::operator == (const String& str) const{
	if (strcmp(buffer,str.buffer)==0)
		return 1;
	else
		return 0;
}

int String::compare(const String & str) const{
    return strcmp(buffer,str.buffer);
}