C++ 写自己的string类(作风：：懒)

系统管理员 2022-08-20 12:16 141阅读 0赞

#include <iostream>
    #include<cstdlib>
    #include <conio.h>
    using namespace std;
    
    
    class Cstring
    {
    private:
    	unsigned int len;
    	char *st;
    	explicit Cstring(const unsigned int i)
    	{
    		len = 0;
    		st = new char[i+1];
    		return;
    	}
    public:
    	~Cstring()
    	{
    		delete []st;
    		st = 0;
    	}
    	explicit	Cstring()
    	{
    		len = 0;
    		st = new char[len+1];
    		st[0] = '\0';
    	}
    	Cstring(const Cstring &s)
    	{
    		len = s.len;
    		st = new char[len + 1];
    		for ( int i = 0; i < len; i++)
    		{
    			st[i] = s[i];
    		}
    		st[len] = '\0';
    		return;
    	}
    	explicit Cstring(const char *const ch)
    	{
    		len = strlen(ch);
    		st = new char[len + 1];
    		for ( int i = 0; i < len; i++)
    		{
    			st[i] = ch[i];
    		}
    		st[len] = '\0';
    		return;
    	}
    	explicit	Cstring(const char ch)
    	{
    		len = 1;
    		st = new char[len + 1];
    		st[0] = ch;
    		st[1] = '\0';
    		return;
    	}
    	char &operator[](unsigned int i)const
    	{
    		if (i > len - 1)
    		{
    			return st[len - 1];
    		}
    		else
    			return st[i];
    	}
    	char &operator[](unsigned int i)
    	{
    		if (i > len - 1)
    		{
    			return st[len - 1];
    		}
    		else
    			return st[i];
    	}
    	Cstring &operator=(const char * const ch)
    	{
    		if (strcmp(st, ch) == 0)
    			return *this;
    		char *p = st;
    		delete []p;
    		p = 0;
    		len = strlen(ch);
    		st = new char[len + 1];
    		for (unsigned int i = 0; i < len; i++)
    		{
    			st[i] = ch[i];
    		}
    		st[len] = '\0';
    		return *this;
    	}
    	Cstring &operator=(const Cstring &s)
    	{
    		if (this == &s)
    			return *this;
    		char *p = st;
    		delete[]p;
    		p = 0;
    		len = s.len;
    		st = new char[len + 1];
    		for ( int i = 0; i < len; i++)
    		{
    			st[i] = s[i];
    		}
    		st[len] = '\0';
    		return *this;
    	}
    	const	Cstring operator+(const Cstring &s)
    	{
    		unsigned int temlen = len + s.len;
    		Cstring temp(temlen);
    		for (unsigned int i = 0; i < len; i++)
    		{
    			temp.st[i] = st[i];
    		}
    		for (unsigned int j = 0; j < s.len; j++)
    		{
    			temp.st[len + j] = s.st[j];
    		}
    		temp.len = temlen;
    		temp.st[temp.len] = '\0';
    		return temp;
    	}
    	const	Cstring operator+(const char *const ch)
    	{
    		unsigned int templen = len + strlen(ch);
    		Cstring temp(templen);
    		for (unsigned int i = 0; i < len; i++)
    		{
    			temp.st[i] = st[i];
    		}
    		for (unsigned int j = 0; j < strlen(ch); j++)
    		{
    			temp.st[len + j] = ch[j];
    		}
    		temp.len = templen;
    		temp.st[temp.len] = '\0';
    		return temp;
    	}
    
    	friend ostream&operator<<(ostream &o, const Cstring &s)
    	{
    		o << s.st;
    		return o;
    	}
    	friend istream&operator>>(istream &in,  Cstring &s)
    	{
    		char ch;
    		int i = 0;
    		while ((ch = cin.get())!='\n')
    		{
    			if (!i)
    			{
    				delete[]s.st;
    				s.st = 0;
    				s.len = i+1;
    				s.st = (char*)realloc(s.st, (s.len+1)*sizeof(char));
    				s.st[i] = ch;
    				s.st[i+1] = '\0';
    				i++;
    			}
    			else
    			{
    				s.len = i + 1;
    				s.st = (char*)realloc(s.st, (s.len + 1)*sizeof(char));
    				s.st[i] = ch;
    				s.st[i + 1] = '\0';
    				i++;
    			}
    		}
    		return in;
    	}
    
    };
    
    int main()
    {
    	Cstring s;
    	s = "123333333";
    	s[4] = '1';
    	Cstring ss(s);
    	cout << ss << endl;
    	
    	system("pause");
    	return 0;
    }