string1.h

大学计算机专业课程中数据结构各章的算法设计

#include<iostream.h>
#include<string.h>
class String1
{
private:
	char *table;
	int len;
public:
	String1(char *str="");
    String1(char ch);
	String1(const String1 &s);
	~String1();

    int length();
	char charAt(int i);
	void output();
	void concat(char *str2);
	void concat(const String1 &s2);

	String1& operator=(char *str);

	String1& operator=(String1 &s1);
    friend ostream & operator<<(ostream & out,String1 &s);
    
	int operator==(char *str);
	int operator==(String1 &s2);
	String1 & operator+=(String1 &s2);
	String1  operator+(String1 &s2);

    String1 subString(int i,int n);
	String1 insert(int i,String1 &s2);
		
	String1 reverse();
		
	String1 remove(int i,int n);

	int String1::indexof(String1 &sub,int start=0);

	int indexof(char ch,int start=0);
	String1 replace (String1 &oldstr,String1 &newstr);
};

String1::String1(char *str)
{
	len=strlen(str);
	table=new char[len+1];
	strcpy(table,str);
}
String1::String1(char ch)
{
	len=1;
	table=new char[len+1];
	table[0]=ch;
	table[1]='\0';
}
String1::String1(const String1 &s)
{
	len =s.len ;
	table=new char[len+1];
	strcpy(table,s.table);
}
String1::~String1()
{
	delete[] table;
	len=0;
}
//求串长度
int String1::length()
{
	return len;
}
////取字符
char String1::charAt(int i)
{
    if(i>0&&i<=len)
		return table[i-1];
	else
		return -1;
}
//////////输出串
void String1::output()
{
	cout<<"s.len="<<len<<" ";
	cout<<"s.table="<<table;
	if(table[len]==0)
		cout<<'0';
	cout<<endl;
}
///连接两串
void String1::concat(char *str)
{
	char *p=this->table;
	int n1=len,n2=strlen(str);
	len =n1+n2;
	table=new char[len+1];
	table=strcpy(table,p);
	for(int i=0;i<n2;i++)
		table[i+n1]=str[i];
	table[len]='\0';

}
void String1::concat(const String1 &s2)
{
	concat(s2.table);
}
////////////////////////////////////////////////////
///////////////////////////////////////////////////
///重载=

String1& String1::operator = (char *str)
{
	len=strlen(str);
	table=new char[len+1];
	strcpy(table,str);
	return *this;
}
String1& String1::operator = (String1 &s1)
{
	delete []table;
	len=s1.length ();
	table=new char[len+1];
	strcpy(table,s1.table );
	return *this;
}
//重载<<

ostream & operator<<(ostream & out,String1 &s)
{
	out<<s.table ;
	return out;
}
//重载=
int String1::operator==(char *str)
{
	return (strcmp(table,str));
}
int String1::operator==(String1 &s2)
{
	return (strcmp(table,s2.table));
}
//重载+=  +
String1& String1::operator += (String1 &s2)

{
String1 s1=*this;
int n1=s1.length ();
int n2=s2.length ();
len=n1+n2;
table=new char[len+1];
strcpy(table,s1.table );
for(int i=0;i<n2;i++)
table[n1+i]=s2.table[i];
table[len]='\0';
return *this;
}
String1 String1::operator + (String1 &s2)
{
	String1 news1=*this;
	news1+=s2;
	return news1;
}

String1 String1::subString(int i,int n)
{
	String1 sub;
	if(i<=0) i=1;
	if(i>len || n==0)
		return sub;
	delete []sub.table;
	sub.len=n;
	if(n>len-i+1)
		sub.len =len-i+1;
	sub.table =new char[sub.len+1];
	i--;
	for(int j=0;j<sub.len ;j++)
		sub.table [j]=table[i+j];
		sub.table [sub.len]='\0';
	return sub;
}
////////有问题
/*
int String1::indexof (char ch,int start)
{
	String1 sub(ch);
	return this->indexof (sub,start);
}*/
//////插入子串

String1 String1::insert(int i,String1 &s2)
{
	return subString(1,i-1)+s2+subString(i,len-i+1);
}
//删除子串
String1 String1::remove(int i,int n)
{
	return subString(1,i-1)+subString(i+n,len-1-n+1);
}
//串的逆转
String1 String1::reverse ()
{
	String1 news1;
	for(int i=len ;i>=1;i--)
	{
		news1+=subString(i,1);
	}
	return news1;
}