Stringクラスの各種操作(動的)

<span style="font-size:18px;">#define _CRT_SECURE_NO_WARNINGS
#define DEFAULT 8
#include<iostream>
#include<assert.h>
#include<string>
using namespace std;
class String
{
private:
	char* _ptr;// 
	size_t _size;// 
	size_t _capacity;// 
private:</span>

<span style="font-size:18px;">// ： < ， 
	void _CheckCapacity(size_t capacity)
	{
		if (_capacity < capacity)
		{
			_capacity = capacity + DEFAULT;
			char* tmp = new char[_capacity];
			strcpy(tmp, _ptr);
			delete[] _ptr;
			_ptr = tmp;
		}
	}
	void Swap(String& s)
	{
		swap(_ptr, s._ptr);
		swap(_size, s._size);
		swap(_capacity, s._capacity);
	}
	void Reserve(size_t capacity)
	{
		_CheckCapacity(capacity);
	}
public:</span>

<span style="font-size:18px;">
</span>

<span style="font-size:18px;">/* ， ， {} ， ；   ， / ， ， */
</span>

<span style="font-size:18px;">
	String(char* ptr = "")
		: _size(strlen(ptr))
		, _capacity(_size + DEFAULT)
	{
		_ptr = new char[_capacity];
		strcpy(_ptr, ptr);
	}
	String(const String& s)
		:_ptr(NULL)
		, _size(0)
		, _capacity(0)
	{
		String tmp(s._ptr);
		Swap(tmp);
	}
	String& operator=(String s)
	{
		if (this != &s)
		{
			Swap(s);
		}
		return *this;
	}
	
	~String()
	{
		if (_ptr)
		{
			delete[] _ptr;
			_size = 0;
			_capacity = 0;
		}
	}
	friend ostream& operator<<(ostream& os, const String& s)
	{
		cout << s._ptr;
		return os;
	}
	friend istream& operator>>(istream& is, String& s)
	{
		s.Reserve(100);
		is.getline(s._ptr,100);
		return is;
	}
public:
	char* GetStr()
	{
		return _ptr;
	}
	void PushBack(char ch)
	{
		_CheckCapacity(_size + 2);
		_ptr[_size++] = ch;
		_ptr[_size] = '\0';
	}
	void PushBack(char* str)
	{
		_CheckCapacity(_size + strlen(str) + 1);
		while (*str)
		{
			_ptr[_size++] = *str++;
		}
		_ptr[_size] = '\0';
	}
	void PopBack()
	{
		_ptr[--_size] = '\0';
	}
	void Insert(size_t pos, char ch)
	{
		assert(pos <= _size);
		_CheckCapacity(_size + 2);
		int i = _size;
		for (; i >= (int)pos; --i)
		{
			_ptr[i + 1] = _ptr[i];
		}
		_ptr[pos] = ch;
		++_size;
	}
	void Insert(size_t pos, char* str)
	{
		assert(pos <= _size);
		int len = strlen(str);
		_CheckCapacity(_size + len + 1);
		int j = _size;
		int i = _size + len;
		for (; j >= (int)pos;)
		{
			_ptr[i--] = _ptr[j--];
		}
		while (*str)
		{
			_ptr[pos++] = *str++;
		}
		_size += len;
	}
	int Find(char ch)
	{
		int count = 0;
		char* tmp = _ptr;
		while (_ptr && (*_ptr))
		{
			if (*_ptr == ch)
			{
				return count;
			}
			else
			{
				++count;
				++_ptr;
			}
		}
		_ptr = tmp;
		return -1;
	}
	int Find(char* str)
	{
		char* tmp = str;
		size_t count = 0;
		size_t recount = count;
		size_t rrcount = 0;
		char* pptr = _ptr;
		while (_ptr)
		{
			while (*str)
			{
				if (*_ptr == *str)
				{
					++_ptr;
					++str;
					++rrcount;
				}
				else
				{
					++_ptr;
					++count;
					if (*str != *tmp)
					{
						str = tmp;
						recount = count;
					}
				}
			}
			recount = count + rrcount - strlen(tmp);
			_ptr = pptr;
			return recount;
		}
		return -1;
	}
public:
	// C 
	bool operator<(const String& s)
	{
		char* s1 = _ptr;
		char* s2 = s._ptr;
		while (s1 && s2)
		{
			if (*s1<*s2)
			{
				return true;
			}
			else if (*s1>*s2)
			{
				return false;
			}
			else
			{
				++s1;
				++s2;
			}
		}
		if (s1 == NULL && s2 != NULL)
		{
			return true;
		}
		return false;
	}
	bool operator<=(const String& s)
	{
		if (*this<s || *this == s)
		{
			return true;
		}
		return false;
	}
	bool operator>(const String& s)
	{
		if (*this <= s)
		{
			return false;
		}
		return true;
	}
	bool operator>=(const String& s)
	{
		if (*this < s)
		{
			return false;
		}
		return true;
	}
	bool operator==(const String& s)
	{
		char* s1 = _ptr;
		char* s2 = s._ptr;
		while (*s1 && *s2)
		{
			if (*s1++ != *s2++)
				return false;
		}
		if (*s1 == *s2)
		{
			return true;
		}
		return false;
	}

	String operator+(const String& s)
	{
		String tmp(_ptr);
		tmp.Insert(_size, s._ptr);
		return tmp;
	}
	String& operator+=(const String& s)
	{
		Insert(_size, s._ptr);
		return *this;
	}
};
// 
void Test1()
{
	String s1("abcd");
	String s2(s1);
	String s3;
	s3 = s2;
	cout << "s1:" << s1 << endl;
	cout << "s2:" << s2 << endl;
	cout << "s3:" << s3 << endl;
}
// ， ， 
void Test2()
{
	String s1("abcd");
	String s2;
	s2.PushBack('e');
	s2.PushBack('f');
	s2.PushBack('g');
	s2.PushBack('h');
	cout << "s1:" << s1 << endl;
	cout << "s2:" << s2 << endl;


	s2.PushBack("abcdef");
	cout << "s2:" << s2 << endl;

	s2.PopBack();
	s2.PopBack();
	s2.PopBack();
	cout << "s2:" << s2 << endl;

	s2.Insert(5, 'x');
	cout << "s2:" << s2 << endl;

	s2.Insert(5, "vbnmg");
	cout << "s2:" << s2 << endl;
}
// 
void Test3()
{
	String s1("abcgefcd");
	int ret1 = s1.Find('x');
	cout << ret1 << endl;

	int ret2 = s1.Find("cd");
	cout << ret2 << endl;
}
// 
void Test4()
{
	String s1("abcdef");
	String s2("abcde");
	if (s1 < s2)
		cout << "True" << endl;
	else
		cout << "False" << endl;

	String s3("abcdef");
	String s4("abcdef");
	if (s3 == s4)
		cout << "True" << endl;
	else
		cout << "False" << endl;

	String s5("abcdefa");
	String s6("abcdef");
	if (s5 <= s6)
		cout << "True" << endl;
	else
		cout << "False" << endl;

	String s7("abcde");
	String s8("abcdef");
	if (s7 > s8)
		cout << "True" << endl;
	else
		cout << "False" << endl;

	String s9("abcdefa");
	String s10("abcdef");
	if (s9 >= s10)
		cout << "True" << endl;
	else
		cout << "False" << endl;
}
// +and+=
void Test5()
{
	String s1("abcdefa");
	String s2("abcdef");
	s1 += s2;
	cout << "s1:" << s1 << endl;
	String s3("abcdefa");
	String s4("abcdef");
	String s5;
	s5 = s3 + s4;
	cout << "s5:" << s5 << endl;

	cin >> s1;
	cout << s1 << endl;
}
int main()
{
	Test1();
	Test2();
	Test3();
	Test4();
	Test5();
	return 0;
}</span>