字符串模拟实现（直接在源代码上实现）
最编程
2024-04-27 19:45:14
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#include<iostream>
#include<string>
#include<assert.h>
using namespace std;
namespace bit
{
class string
{
friend ostream& operator<<(ostream& _cout, const bit::string& s);
friend istream& operator>>(istream& _cin, bit::string& s);
public:
typedef char* iterator;
public:
//构造函数
string(const char* str = "")
{
_str = new char[strlen(str)+1];
for (int i = 0; i < strlen(str); i++)
{
_str[i] = str[i];
}
_size = strlen(str);
_str[_size] = '\0';
_capacity = strlen(str);
}
string(const string& s)
{
_str = new char[strlen(s._str)+1];
for (int i = 0; i < strlen(s._str); i++)
{
_str[i] = s._str[i];
}
_size = strlen(s._str);
_str[_size] = '\0';
_capacity = strlen(s._str);
}
string& operator=(const string& s);
//析构
~string()
{
delete[] _str;
_str = nullptr;
_size = _capacity = 0;
}
//
// iterator
iterator begin()
{
return _str;
}
iterator end()
{
return _str + _size;
}
/
// modify
void push_back(char c)
{
if (_size == _capacity)
{
reserve(_capacity == 0 ? 4 : 2 * _capacity);
}
_str[_size] = c;
++_size;
_str[_size] = '\0';
}
string& operator+=(char c);
void append(const char* str)
{
size_t len = strlen(str);
if (_size + len > _capacity)
{
reserve(_size + len);
}
strcpy(_str + _size, str);
_size += len;
}
string& operator+=(const char* str);
void clear()
{
_size = 0;
_str[_size] = '\0';
}
void swap(string& s)
{
char* tempstr = _str;
_str = s._str;
s._str = tempstr;
int tcp = _capacity;
_capacity = s._capacity;
s._capacity = tcp;
int tsz = _size;
_size = s._size;
s._size = tsz;
}
const char* c_str()const
{
return _str;
}
/
// capacity
size_t size()const
{
return _size;
}
size_t capacity()const
{
return _capacity;
}
bool empty()const
{
return _size == 0;
}
void resize(size_t n, char c = '\0')
{
if (n <= _size)
{
_str[n] = '\0';
_size = n;
}
else
{
reserve(n);
for (size_t i = _size; i < n; i++)
{
_str[i] = c;
}
_str[n] = '\0';
_size = n;
}
}
void reserve(size_t n)
{
if (n > _capacity)
{
char* tmp = new char[n + 1];
strcpy(tmp, _str);
delete[] _str;
_str = tmp;
_capacity = n;
}
}
/
// access
char& operator[](size_t index)
{
return _str[index];
}
const char& operator[](size_t index)const
{
return _str[index];
}
/
//relational operators
bool operator<(const string& s)
{
int end1 = _size;
int end2 = s._size;
while (end1!=0&&end2!=0)
{
if (_str[end1] < s._str[end2])
{
return true;
}
else if (_str[end1] == s._str[end2])
{
end1++;
end2++;
}
else
return false;
}
if (end1 == 0&&end2!=0)
{
return true;
}
else
{
return false;
}
}
bool operator<=(const string& s)
{
return !(*this > s);
}
bool operator>(const string& s)
{
return !(*this < s || *this == s);
}
bool operator>=(const string& s)
{
return !(*this < s);
}
bool operator==(const string& s)
{
if (_size!= s._size)
{
return false;
}
for (int i = 0; i < _size; i++)
{
if (_str[i] != s._str[i])
{
return false;
}
}
return true;
}
bool operator!=(const string& s)
{
return !(*this == s);
}
// 返回c在string中第一次出现的位置
size_t find(char c, size_t pos = 0) const
{
assert(pos < _size);
for (size_t i = pos; i < _size; i++)
{
if (_str[i] == c)
return i;
}
return npos;
}
// 返回子串s在string中第一次出现的位置
size_t find(const char* s, size_t pos = 0) const
{
assert(pos < _size);
const char* p = strstr(_str + pos, s);
if (p)
{
return p - _str;
}
else
{
return npos;
}
}
// 在pos位置上插入字符c/字符串str，并返回该字符的位置
string& insert(size_t pos, char c)
{
assert(pos <= _size);
// 扩容2倍
if (_size == _capacity)
{
reserve(_capacity == 0 ? 4 : 2 * _capacity);
}
size_t end = _size + 1;
while (end > pos)
{
_str[end] = _str[end - 1];
--end;
}
_str[pos] = c;
++_size;
return *this;
}
string& insert(size_t pos, const char* str)
{
assert(pos <= _size);
size_t len = strlen(str);
if (_size + len > _capacity)
{
// 扩容
reserve(_size + len);
}
size_t end = _size + len;
while (end > pos + len - 1)
{
_str[end] = _str[end - len];
end--;
}
strncpy(_str + pos, str, len);
_size += len;
return *this;
}
// 删除pos位置上的元素，并返回该元素的下一个位置
string& erase(size_t pos=0, size_t len=npos)
{
assert(pos < _size);
if (len == npos || len >= _size - pos)
{
_str[pos] = '\0';
_size = pos;
}
if (len == npos || len >= _size - pos)
{
_str[pos] = '\0';
_size = pos;
}
return *this;
}
private:
char* _str;
size_t _capacity;
size_t _size;
public:
static const int npos;
};
const int string::npos = -1;
string& string::operator=(const string& s)
{
char* tmp = new char[s._capacity + 1];
strcpy(tmp, s._str);
delete[] _str;
_str = tmp;
_size = s._size;
_capacity = s._capacity;
return *this;
}
string& string::operator+=(char c)
{
push_back(c);
return *this;
}
string& string::operator+=(const char* str)
{
append(str);
return *this;
}
ostream& operator<<(ostream& _cout, const bit::string& s)
{
_cout << s._str << endl;
return _cout;
}
istream& operator>>(istream& _cin, bit::string& s)
{
s.clear();
char ch;
//in >> ch;
ch = _cin.get();
char buff[128];
size_t i = 0;
while (ch != ' ' && ch != '\n')
{
buff[i++] = ch;
// [0,126]
if (i == 127)
{
buff[127] = '\0';
s += buff;
i = 0;
}
ch = _cin.get();
}
if (i > 0)
{
buff[i] = '\0';
s += buff;
}
return _cin;
}
}
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