#pragma once
#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<assert.h>
using namespace std;
namespace liu
{
class string
{
public:
using iterator = char*;
using const_iterator = const char*;
//string();//无参构造
string(const string& s);//拷贝构造
string(const char* str="");//有参构造
~string();//析构
char& operator[](size_t i)
{
assert(i < _size);
return _str[i];
}
const char& operator[](size_t i)const
{
assert(i < _size);
return _str[i];
}
size_t size()const
{
return _size;
}
const char* c_str()const//c_str函数，返回_str
{
return _str;
}
iterator begin()
{
return _str;
}
iterator end()
{
return _str+_size;
}
const_iterator begin()const
{
return _str;
}
const_iterator end()const
{
return _str + _size;
}
void clear()
{
_str[0] = '\0';
_size = 0;
}
void reserve(size_t n);
void push_back(char ch);
void append(const char* ch);
string& operator+=(char ch);
string& operator+=(const char* ch);
void insert(size_t pos,char ch);
void insert(size_t pos,const char* ch);
void erase(size_t pos,size_t len=npos);
size_t find(char ch,size_t pos=0);
size_t find(const char* ch,size_t pos=0);
string substr(size_t pos = 0, size_t len = npos)const;
string& operator=(string s);
void swap(string& s);
private:
char* _str=nullptr;
size_t _size=0;
size_t _capacity=0;
public:
//c++的特殊处理
static const size_t npos=-1;
};
void swap(string& s1, string& s2);
bool operator==(const string& lhs, const string& rhs);
bool operator!=(const string& lhs, const string& rhs);
bool operator<(const string& lhs, const string& rhs);
bool operator>(const string& lhs, const string& rhs);
bool operator<=(const string& lhs, const string& rhs);
bool operator>=(const string& lhs, const string& rhs);
ostream& operator<<(ostream& os,const string& str);
istream& operator>>(istream& is, string& str);
istream& getline(istream& is, string& str,char delim='\n');
}
#include"string.h"
namespace liu
{
//const size_t string:: npos = -1;
/*string::string()
:_str(new char[1] {'\0'})
, _size(0)
, _capacity(0)
{}*/
string::string(const char* str)
//:_str(new char[strlen(str)+1])//出去字符串的空间，还要保留一个'\0'的空间，所以开辟的空间要加1
//,_size(strlen(str))
//,_capacity(strlen(str))
:_size(strlen(str))
{
_str = new char[_size + 1];
_capacity = _size;
strcpy(_str, str);
}
/*string::string(const string& s)
{
_str = new char[s._capacity+1];
strcpy(_str,s._str);
_size = s._size;
_capacity = s._capacity;
}*/
string::string(const string& s)
{
string tmp(s._str);
swap(tmp);
}
string::~string()
{
delete[] _str;
_str = nullptr;
_size = 0;
_capacity = 0;
}
void string::reserve(size_t n)
{
if (n>_capacity)
{
cout << "reserve:" << n << endl;
char* tmp = new char[n + 1];
strcpy(tmp,_str);
delete _str;
_str = tmp;
_capacity = n;
}
}
void string::push_back(char ch)
{
/*if (_size==_capacity)
{
reserve(_capacity==0?4:_capacity*2);
}
_str[_size++] = ch;*/
insert(_size,ch);
}
void string::append(const char* ch)
{
/*size_t len = strlen(ch);
if (_size+len>_capacity)
{
size_t NewCapacity = 2 * _capacity;
if (NewCapacity < _size + len)
NewCapacity = _size + len;
reserve(NewCapacity);
}
strcpy(_str + _size, ch);
_size += len;*/
insert(_size,ch);
}
string& string::operator+=(char ch)
{
push_back(ch);
return *this;
}
string& string::operator+=(const char* ch)
{
append(ch);
return *this;
}
void string::insert(size_t pos, char ch)
{
if (_size == _capacity)
{
reserve(_capacity == 0 ? 4 : _capacity * 2);
}
size_t end = _size+1;
while (end>pos)
{
_str[end] = _str[end-1];
end--;
}
_str[pos] = ch;
_size++;
}
void string::insert(size_t pos, const char* ch)
{
assert(pos<=_size);
size_t len = strlen(ch);
if (_size + len > _capacity)
{
size_t NewCapacity = 2 * _capacity;
if (NewCapacity < _size + len)
NewCapacity = _size + len;
reserve(NewCapacity);
}
size_t end = _size+len;
while (end>pos+len-1 )
{
_str[end] = _str[end-len];
--end;
}
for (size_t i=0;i<len;i++)
{
_str[pos + i] = ch[i];
}
_size += len;
}
void string::erase(size_t pos, size_t len)
{
assert(pos<_size);
if (len>_size-pos)
{
_str[pos] = '\0';
_size = pos;
}
else
{
size_t end = pos + len;
while (end<=_size)
{
_str[end - len] = _str[end];
++end;
}
_size -= len;
}
}
size_t string::find(char ch, size_t pos)
{
assert(pos<_size);
for (size_t i=pos;i<_size;i++)
{
if (ch==_str[i])
{
return i;
}
}
return npos;
}
size_t string::find(const char* ch, size_t pos)
{
const char* ptr = strstr(_str+pos,ch);
if (ptr==nullptr)
{
return npos;
}
else
{
return ptr - _str;
}
}
string string::substr(size_t pos , size_t len )const
{
if (len>(_size-pos))
{
len = _size - pos;
}
liu::string sub;
sub.reserve(len);
for (size_t i=0;i<len;i++)
{
sub += _str[pos + i];
}
return sub;
}
//传统写法
//string& string::operator=(const string& s)
//{
// if (this != &s)
// {
// delete[] _str;
// _str = new char[s._capacity + 1];
// strcpy(_str, s._str);
// _size = s._size;
// _capacity = s._capacity;
// }
// return *this;
//}
string& string::operator=( string s)
{
/*if (this != &s)
{
string tmp(s._str);
swap(tmp);
}*/
swap(s);
return *this;
}
void string::swap(string& s)
{
std::swap(_str,s._str);
std::swap(_size,s._size);
std::swap(_capacity,s._capacity);
}
//
void swap(string& s1, string& s2)
{
s1.swap(s2);
}
bool operator==(const string& lhs, const string& rhs)
{
return strcmp(lhs.c_str(),rhs.c_str())==0;
}
bool operator!=(const string& lhs, const string& rhs)
{
return !(lhs == rhs);
}
bool operator<(const string& lhs, const string& rhs)
{
return strcmp(lhs.c_str(),rhs.c_str())<0;
}
bool operator>(const string& lhs, const string& rhs)
{
return !(lhs < rhs || lhs == rhs);
}
bool operator<=(const string& lhs, const string& rhs)
{
return lhs < rhs || lhs == rhs;
}
bool operator>=(const string& lhs, const string& rhs)
{
return !(lhs < rhs);
}
ostream& operator<<(ostream& os, const string& str)
{
//os<<"\"";
//os << '"';
for (size_t i=0;i<str.size();i++)
{
cout << str[i];
}
return os;
}
istream& operator>>(istream& is, string& str)
{
str.clear();
//str.reserve(1024);
int i = 0;
char buff[256];
char ch;
ch = is.get();
while (ch!=' '&&ch!='\n')
{
buff[i++] = ch;
if (i==255)
{
buff[i] = '\0';
str += buff;
i = 0;
}
ch = is.get();
}
if (i>0)
{
buff[i] = '\0';
str += buff;
}
return is;
}
istream& getline(istream& is, string& str, char delim)
{
str.clear();
int i = 0;
char buff[256];
char ch;
ch = is.get();
while (ch != delim)
{
buff[i++] = ch;
if (i == 255)
{
buff[i] = '\0';
str += buff;
i = 0;
}
ch = is.get();
}
if (i > 0)
{
buff[i] = '\0';
str += buff;
}
return is;
}
}
构造函数：
string(const char* str="")//当实例化时，没有给参数，就使用这里的缺省参数，这个参数就相当于给对象赋值了一个'\0'
:_size(strlen(str))
{
_capacity = _size;
_str = new char[_size + 1];
strcpy(_str,str);
}