hello，各位小伙伴，本篇文章跟大家一起学习《C++：string的的模拟实现》，感谢大家对我上一篇的支持，如有什么问题，还请多多指教 ！
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话不多说，开始进入正题
文章目录
- :heartbeat:模拟实现string头文件
- 1.:maple_leaf:iterator begin();和iterator end();:maple_leaf:const_iterator begin() const;和const_iterator end() const;
- 2.:maple_leaf:构造函数和拷贝构造函数
- :leaves:构造函数
- :leaves:拷贝构造函数
- 3.:maple_leaf:析构函数
- 4.:maple_leaf:赋值重载函数
- 5.:maple_leaf:const char* c_str() const;
- 6.:maple_leaf:size_t size() const;
- 7. :maple_leaf:[]运算符重载
- :leaves:char& operator[](size_t pos);
- :leaves:const char& operator[](size_t pos) const;
- 8.:maple_leaf:void reserve(size_t n);
- 9.:maple_leaf:void push_back(char ch);
- 10.:maple_leaf:void append(const char* str);
- 11.:maple_leaf:+=运算符重载函数
- :leaves:string& operator+=(char ch);
- :leaves:string& operator+=(const char* str);
- 12.:maple_leaf:insert的实现
- :leaves:void insert(size_t pos, char ch);
- :leaves:void insert(size_t pos, const char* str);
- 13.:maple_leaf:void erase(size_t pos = 0, size_t len = npos);
- 14.:maple_leaf:find函数实现
- :leaves:size_t find(char ch, size_t pos);
- :leaves:size_t find(const char* str, size_t pos);
- 15.:maple_leaf:swap函数的实现
- 16.:maple_leaf:substr的实现
- 17.:maple_leaf:运算符重载
- 18.:maple_leaf:>>重载函数和重载函数
- :leaves:
class string
{
public:
typedef char* iterator;
typedef const char* const_iterator;
iterator begin();
iterator end();
const_iterator begin() const;
const_iterator end() const;
//string();
string(const char* str = "");
string(const string& s);
string& operator=(string s);
~string();
const char* c_str() const;
size_t size() const;
char& operator[](size_t pos);
const char& operator[](size_t pos) const;
void reserve(size_t n);
void push_back(char ch);
void append(const char* str);
string& operator+=(char ch);
string& operator+=(const char* str);
void insert(size_t pos, char ch);
void insert(size_t pos, const char* str);
void erase(size_t pos = 0, size_t len = npos);
size_t find(char ch, size_t pos = 0);
size_t find(const char* str, size_t pos = 0);
void swap(string& s);
string substr(size_t pos = 0, size_t len = npos);
bool operator (istream& is, string& str);
ostream& operator
return _str;
}
string::iterator string::end()
{
return _str + _size;
}
string::const_iterator string::begin() const
{
return _str;
}
string::const_iterator string::end() const
{
return _str + _size;
}
_str = new char[_size + 1];
_capacity = _size;
strcpy(_str, str);
}
string tmp(s._str);
swap(tmp);
}
_size = _capacity = 0;
delete[] _str;
_str = nullptr;
}
if(this != &s)
{
char* tmp = new char[s._capacity + 1];
strcpy(tmp,s._str);
delete[] _str;
_size = s._size;
_capacity = s._capacity;
_str = tmp;
}
return *this;
}
swap(s);// 让别人来干活
return *this;
}
return _str;
}
return _size;
}
assert(pos
🍃在实现insert之后的写法：
void string::append(const char* str) { insert(_size,str); }11.🍁+=运算符重载函数
🍃string& operator+=(char ch);
string& string::operator+=(char ch) { push_back(ch); return *this; }🍃string& operator+=(const char* str);
string& string::operator+=(const char str) { append(str); return *this; }12.🍁insert的实现
🍃void insert(size_t pos, char ch);
void string::insert(size_t pos, char ch) { assert(pos size_t newcapacity = _capacity == 0 ? 4 : 2*_capacity; reserve(newcapacity); } size_t end = _size + 1; while(end pos) { _str[end] = _str[end - 1]; --end; } _str[pos] = ch; ++_size; }🍃void insert(size_t pos, const char* str);
void string::insert(size_t pos, const char* str) { assert(pos _capacity) { reserve(_size + len); } size_t end = _size + len; while(end >= pos + len) { _str[end] = _str[end - len]; --end; } memcpy(_str + pos,str,len); // 由于strcpy会将后面的字符覆盖，所以这里要用memcpy _size += len; }13.🍁void erase(size_t pos = 0, size_t len = npos);
const size_t string::npos = -1; void string::erase(size_t pos, size_t len) { assert(_size > pos); if(len > _size - pos) { _str[pos] = '\0'; _size = pos; } else { strcpy(_str + pos, _str + pos + len); _size -= len; } }14.🍁find函数实现
🍃size_t find(char ch, size_t pos);
size_t string::find(char ch, size_t pos) { assert(_size > pos); int index = pos; // npos在前面有定义 while (index🍃size_t find(const char* str, size_t pos);
size_t string::find(const char* str, size_t pos) { char* p = strstr(_str + pos, str); return p - _str; }15.🍁swap函数的实现
void string::swap(string& s) { std::swap(_str,s._str); std::swap(_size,s._size); std::swap(_capacity,s._capacity); }16.🍁substr的实现
string string::substr(size_t pos, size_t len) { if(len >= _size - pos) { string tmp(_str + pos); return tmp; } else { string tmp; tmp.reserve(len); for(int i = 0;i17.🍁运算符重载
bool operator(const string& s) const; bool operator=(const string& s) const; bool operator==(const string& s) const; bool operator!=(const string& s) const;
bool string::operator return strcmp(_str, s._str)
18.🍁>>重载函数和重载函数
由于流提取需要将整个值改变，所以需要清空原本的值，所以引用函数clear()。
由于流提取会自动忽略空格和换行，所以我们用get()函数来解决流提取问题
void string::clear() { _str[0] = '\0'; _size = 0; } istream& My_string::operator>> (istream& is, string& str) { str.clear(); char buff[128]; char ch = is.get(); int i = 0; while (ch != ' ' && ch != '\n') { buff[i] = ch;// 临时变量，能够快速生成 ++i; if (i == 127)// 当buff已经满了，进行+=操作 { buff[i] = '\0'; str += buff; i = 0;// 记得i要置为0 } ch = is.get();// 提取下一个字符 } if (i > 0)// 当还有字符没有进行插入时，继续进行+=操作 { buff[i] = '\0'; str += buff; } return is; }🍃 for (size_t i = 0; i
