String (Code)

实现了大部分基础的string操作，重载了”-“运算符，”!”反转运算符
算是一次小小的练手吧

头文件：

#include <iostream>
using namespace std;

class TString {
private:
	char *content;
	int   len;
public:
	TString();
	TString(const char *p);
	TString(const TString &p);
	~TString();
	friend ostream &operator<<(ostream &out, const TString &p);
	friend istream &operator>>(istream &in, TString &p);
	TString& operator=(const TString &p);
	TString& operator=(const char *p);
	friend bool operator!=(const TString&, const TString&);
	friend bool operator==(const TString&, const TString&);
	friend TString operator+(const TString&, const TString&);
	friend TString operator+(const TString&, const char&);
	friend TString operator+(const char&, const TString&);
	friend TString operator+(const TString&, const char*);
	friend TString operator+(const char*, const TString&);
	const char* c_str() const;
	TString& operator+=(const TString&);
	TString& operator+=(const char&);
	friend TString operator-(const TString&, const TString&);
	friend int find(const TString&, const TString&);
	char& operator[](const int);
	const char& operator[](const int)const;
	TString& erase(int, int);
	friend TString operator-(const TString&, const char&);
	friend TString operator-(const TString&, const char*);
	TString& operator-=(const TString&);
	TString& operator-=(const char&);
	friend TString operator*(TString&, const int&);
	TString& operator*=(const int&);
	friend TString operator!(TString&);
	friend bool operator<(const TString&, const TString&);
	friend bool operator<=(const TString&, const TString&);
	friend bool operator>(const TString&, const TString&);
	friend bool operator>=(const TString&, const TString&);
	int length();
	friend int TStringLen(const TString &);
};

具体实现：

#include <iostream>
#include <stdlib.h>
#include <string.h>
#include "TString.h"
using namespace std;

TString::TString()
{
	content = NULL;
	len = 0;
}
TString::TString(const char *p)
{
	if (p == NULL)
	{
		content = NULL;
		len = 0;
		return;
	}
	len = strlen(p);
	if (len == 0)
		content = NULL;
	else
	{
		content = new(nothrow) char[len + 1];
		if (content == NULL)
			len = 0;
		else
			memcpy(content, p, len + 1);
	}
}
TString::TString(const TString &p)
{
	if (p.content == NULL)
	{
		content = NULL;
		len = 0;
		return;
	}
	len = p.len;
	if (len == 0)
	{
		content = NULL;
		return;
	}
	content = new(nothrow) char[len + 1];
	memcpy(content, p.content, len + 1);
}
TString::~TString()
{
	if (content != NULL)
		delete[]content;
}
ostream &operator<<(ostream &out, const TString &p)
{
	if (p.content == NULL)
	{
		out << "<NULL>";
		return out;
	}
	out << p.content;
	return out;
}
istream &operator>>(istream &in, TString &p)
{
	char tmp[2049];
	in >> tmp;
	p.len = strlen(tmp);
	p.content = new(nothrow)  char[p.len + 1];
	if (p.content == NULL)
		p.len = 0;
	else
		memcpy(p.content, tmp, p.len + 1);
	return in;
}
bool operator!=(const TString& a, const TString& b)
{
	if (a.len == 0 && b.len == 0)
		return false;
	if (a.len != b.len)
		return true;
	if (strcmp(a.content, b.content) != 0)
		return true;
	return false;
}
bool operator==(const TString& a, const TString& b)
{
	if (a.len == 0 && b.len == 0)
		return true;
	if (a.len != b.len)
		return false;
	if (strcmp(a.content, b.content) == 0)
		return true;
	return false;
}
TString &TString::operator=(const TString &a)
{
	if (content == a.content)
		return *this;

	if (content)
		delete[]content;

	if (a.content)
	{
		len = a.len;
		content = new(nothrow) char[len + 1];
		memcpy(content, a.content, len + 1);
		return *this;
	}
	else
	{
		content = NULL;
		len = 0;
		return *this;
	}
}
TString &TString::operator=(const char *p)
{
	if (content == p)
		return *this;

	if (content)
		delete[]content;

	if (p&&*p)
	{
		len = strlen(p);
		content = new(nothrow) char[len + 1];
		memcpy(content, p, len + 1);
		return *this;
	}
	else
	{
		content = NULL;
		len = 0;
		return *this;
	}
}
TString operator+(const TString&a, const TString&b)
{
	TString c;
	c.len = a.len + b.len;
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	c.content = new(nothrow) char[c.len + 1];
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	memcpy(c.content, a.content, a.len);
	memcpy(&c.content[a.len], b.content, b.len);
	c.content[c.len] = '\0';
	return c;
}
TString operator+(const TString&a, const char&b)
{
	TString c;
	c.len = a.len + 1;
	c.content = new(nothrow) char[c.len + 1];
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	memcpy(c.content, a.content, a.len);
	c.content[a.len] = b;
	c.content[a.len + 1] = '\0';
	return c;
}
TString operator+(const char&b, const TString&a)
{
	TString c;
	c.len = a.len + 1;
	c.content = new(nothrow) char[c.len + 1];
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	c.content[0] = b;
	memcpy(&c.content[1], a.content, a.len + 1);
	return c;
}
TString operator+(const TString&a, const char*b)
{
	if (b == NULL)
		return a;
	TString c;
	int lenb = strlen(b);
	c.len = a.len + lenb;
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	c.content = new(nothrow) char[c.len + 1];
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	memcpy(c.content, a.content, a.len);
	memcpy(&c.content[a.len], b, lenb);
	c.content[c.len] = '\0';
	return c;
}
TString operator+(const char*b, const TString&a)
{
	if (b == NULL)
		return a;
	TString c;
	int lenb = strlen(b);
	c.len = a.len + lenb;
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	c.content = new(nothrow) char[c.len + 1];
	if (c.len == 0)
	{
		c.content = NULL;
		return c;
	}
	memcpy(c.content, b, lenb);
	memcpy(&c.content[lenb], a.content, a.len + 1);
	return c;
}
TString& TString::operator+=(const TString& c)
{
	if (c.content == NULL)
		return *this;
	if (this == &c)
	{
		TString c2(*this);
		return *this += c2;
	}
	len += c.len;
	char *p_old = content;
	content = new char[len + 1];
	memcpy(content, p_old, len - c.len);
	memcpy(&content[len - c.len], c.content, c.len + 1);
	delete[] p_old;
	return *this;
}
TString& TString::operator+=(const char& c)
{
	len += 1;
	char *p_old = content;
	content = new char[len + 1];
	memcpy(content, p_old, len - 1);
	content[len - 1] = c;
	content[len] = '\0';
	delete[] p_old;
	return *this;
}
const char* TString::c_str() const
{
	return content;
}
char& TString::operator[](const int index)
{
	return content[index];
}
const char& TString::operator[](const int index)const
{
	return content[index];
}
int find(const TString& a, const TString& b)		//kmp算法
{
	int *p = new int[a.len + 1];
	int n = a.len, m = b.len;
	int i = 0, j = -1;
	p[0] = -1;
	while (i<m)
	{
		while (j >= 0 && b[i] != b[j])
			j = p[j];
		i++,j++;
		p[i] = j;
	}
	i = 0, j = 0;
	while (i<n)
	{
		while (j >= 0 && a[i] != b[j])
			j = p[j];
		i++, j++;
		if (j == m)
		{
			delete []p;
			return i - j;
		}
	}
	delete[]p;
	return -1;
}
TString& TString::erase(int pos, int n)
{
	char *p_old = content;
	len -= n;
	content = new char[len + 1];
	for (int i = 0; i < pos; i++)
		content[i] = p_old[i];
	for (int i = pos; i<len; i++)
		content[i] = p_old[i + n];
	*(content + len) = '\0';
	return *this;
}
TString operator-(const TString&a, const TString&b)
{
	TString c = a;
	int k = find(a, b);
	if (k == -1)
		return a;
	c.erase(k, b.len);
	return c;
}
TString operator-(const TString&a, const char*b)
{
	TString c = a;
	int k = find(a, b);
	if (k == -1)
		return a;
	c.erase(k, strlen(b));
	return c;
}
TString operator-(const TString&a, const char&b)
{
	TString c = a;
	for(int i=0;i<c.len;i++)
		if (c.content[i] == b)
		{
			c.erase(i, 1);
			return c;
		}
	return c;
}
TString &TString::operator-=(const TString &b)
{
	*this = *this - b;
	return *this;
}
TString &TString::operator-=(const char &b)
{
	*this = *this - b;
	return *this;
}
TString operator*(TString&a, const int&n)
{
	int i = 1;
	TString c;
	for (int i = 1; i <= n; i++)
		c += a;
	return c;
}
TString &TString::operator*=(const int &n)
{
	*this = *this * n;
	return *this;
}
TString operator!(TString& a)
{
	TString c(a);
	for (int i = 0; i <= c.len / 2 - 1; i++)
	{
		char d = c.content[i];
		c.content[i] = c.content[c.len - i - 1];
		c.content[c.len - i - 1] = d;
	}
	return c;
}
bool operator<(const TString& a, const TString& b)
{
	if (a.len == 0 && b.len == 0)
		return false;
	if (a.len == 0 && b.len != 0)
		return true;
	if (a.len != 0 && b.len == 0)
		return false;
	if (strcmp(a.content, b.content) < 0)
		return true;
	return false;
}
bool operator<=(const TString& a, const TString& b)
{
	if (a.len == 0 && b.len == 0)
		return true;
	if (a.len == 0 && b.len != 0)
		return true;
	if (a.len != 0 && b.len == 0)
		return false;
	if (strcmp(a.content, b.content) <= 0)
		return true;
	return false;
}
bool operator>(const TString& a, const TString& b)
{
	if (a.len == 0 && b.len == 0)
		return false;
	if (a.len == 0 && b.len != 0)
		return false;
	if (a.len != 0 && b.len == 0)
		return true;
	if (strcmp(a.content, b.content) > 0)
		return true;
	return false;
}
bool operator>=(const TString& a, const TString& b)
{
	if (a.len == 0 && b.len == 0)
		return true;
	if (a.len == 0 && b.len != 0)
		return false;
	if (a.len != 0 && b.len == 0)
		return true;
	if (strcmp(a.content, b.content) >= 0)
		return true;
	return false;
}
int TString::length()
{
	return len;
}
int TStringLen(const TString &a)
{
	return a.len;
}