【C++】—— string模拟实现（二）https://developer.aliyun.com/article/1621433
HL :: string 源码
#pragma once #include<iostream> #include<cassert> template <typename T> void Swap(T& x, T& y) { T tmp = x; x = y; y = tmp; } namespace HL { class string { friend std::ostream& operator<<(std::ostream& out, const HL::string& str); friend std::istream& operator>>(std::istream& in, HL::string& str); public: //构造函数 /*string() { _str = new char[1]; _str[0] = '\0'; _size = 0; _capacity = 0; } string(char ch) { _str = new char[1]; _str[0] = ch; _size = 0; _capacity = 0; }*/ string(char ch = '\0') { _str = new char[2]; _str[0] = ch; _str[1] = '\0'; _size = 1; _capacity = 1; } string(const char* s) { size_t len = strlen(s); _str = new char[len + 1]; memcpy(_str, s, len + 1); _size = len; _capacity = len; } string(const char* s, size_t n) { size_t len = strlen(s); if (n > len) { n = len; } _str = new char[n + 1]; memcpy(_str, s, n); _str[n] = '\0'; _size = n; _capacity = n; } string(const string& str) { _str = new char[str._capacity + 1]; memcpy(_str, str._str, str._size + 1); _size = str._size; _capacity = str._capacity; } string(size_t n, char c) { _str = new char[n + 1]; for (size_t i = 0; i < n; i++) { _str[i] = c; } _str[n] = '\0'; _size = n; _capacity = n; } ~string() { delete[] _str; _str = nullptr; _size = _capacity = 0; } /*string& operator=(const string& str) { delete[] _str; _str = new char[str._capacity]; memcpy(_str, str._str, str._size + 1); _size = str._size; _capacity = str._capacity; return *this; }*/ /*string& operator= (const string& str) { string tmp(str); Swap(_str, tmp._str); Swap(_size, tmp._size); Swap(_capacity, tmp._capacity); return *this; }*/ string& operator= (const string& str) { string tmp(str); swap(tmp); return *this; } /*string& operator= (const char* s) { size_t len = strlen(s); delete[] _str; _str = new char[len + 1]; memcpy(_str, s, len + 1); _size = _capacity = len; return *this; }*/ string& operator= (const char* s) { string tmp(s); Swap(_str, tmp._str); Swap(_size, tmp._size); Swap(_capacity, tmp._capacity); return *this; } string& operator= (char c) { delete[] _str; _str = new char[2]; _str[0] = c; _str[1] = '\0'; _size = _capacity = 1; return *this; } //string& operator= (char c) //{ // string tmp(c); // Swap(_str, tmp._str); // Swap(_size, tmp._size); // Swap(_capacity, tmp._capacity); // return *this; //} //迭代器 typedef char* iterator; typedef const char* const_iterator; iterator begin() { return _str; } iterator end() { return (_str + _size); } const_iterator begin() const { return _str; } const_iterator end() const { return (_str + _size); } //下标访问 [ ] char& operator[] (size_t pos) { assert(pos >= 0 && pos < _size); return *(_str + pos); } const char& operator[] (size_t pos) const { assert(pos >= 0 && pos < _size); return *(_str + _size); } //扩容 void reserve(size_t n) { if (n > _capacity) { char* s = new char[n + 1]; memcpy(s, _str, _size); delete[] _str; _str = s; _capacity = n; } } //增 void push_back(char c) { if (_size >= _capacity) { reserve((_capacity == 0) ? 4 : 2 * _capacity); } _str[_size] = c; _size++; _str[_size] = '\0'; } void append(const string& str) { size_t n = _size + str._size; if (n > _capacity) { reserve(n); } for (int i = 0; i < str._size; i++) { _str[_size + i] = str._str[i]; } _size += str._size; _str[_size] = '\0'; } void append(const char* s) { size_t len = strlen(s); size_t n = _size + len; if (n > _capacity) { reserve(n); } for (int i = 0; i < len; i++) { _str[_size + i] = s[i]; } _size = n; _str[_size] = '\0'; } void append(size_t n, char c) { if (_size + n > _capacity) { reserve(_size + n); } for (int i = 0; i < n; i++) { _str[_size + i] = c; } _size += n; _str[_size] = '\0'; } string& operator+=(const string& str) { this->append(str); return *this; } string& operator+=(const char* s) { this->append(s); return *this; } string& operator+=(char c) { this->push_back(c); return *this; } //insert 、erase void insert(size_t pos, const string& str) { assert(pos >= 0 && pos < _size); size_t len = str._size; size_t n = _size + len; if (n > _capacity) { reserve(n); } //挪动数据 for (size_t i = n; i >= pos + len; i--) { _str[i] = _str[i - len]; } memcpy(_str + pos, str._str, str._size); _size += str._size; _str[_size] = '\0'; } void insert(size_t pos, const char* s) { assert(pos >= 0 && pos < _size); size_t len = strlen(s); size_t n = _size + len; if (n > _capacity) { reserve(n); } //挪动数据 for (size_t i = n; i >= pos + len; i--) { _str[i] = _str[i - len]; } memcpy(_str + pos, s, len); _size += len; _str[_size] = '\0'; } void insert(size_t pos, size_t n, char c) { assert(pos >= 0 && pos < _size); if (_size + n > _capacity) { reserve(_size + n); } //挪动数据 for (size_t i = _size+n; i >= pos + n; i--) { _str[i] = _str[i - n]; } for (size_t i = 0; i < n; i++) { _str[pos + i] = c; } _size += n; _str[_size] = '\0'; } void erase(size_t pos, size_t len = npos) { assert(pos >= 0 && pos < _size); if (len == npos) { _str[0] = '\0'; _size = 0; return; } for (size_t i = pos; (len + i) < _size; i++) { _str[i] = _str[i + len]; } _size -= len; _str[_size] = '\0'; } //find size_t find(const string& str, size_t pos = 0) { assert(pos >= 0 && pos < _size); char* tmp = strstr(_str + pos, str._str); if (tmp == nullptr) { return -1; } return tmp - _str; } size_t find(const char* s, size_t pos = 0) { assert(pos >= 0 && pos < _size); char* tmp = strstr(_str + pos, s); if (tmp == nullptr) { return -1; } return tmp - _str; } size_t find(char c, size_t pos = 0) { assert(pos >= 0 && pos < _size); for (size_t i = pos; i < _size; i++) { if (_str[i] == c) { return i; } } return -1; } //swap void swap(string& str) { Swap(_str, str._str); Swap(_size, str._size); Swap(_capacity, str._capacity); } //c_str const char* c_str() const { return _str; } char* c_str() { return _str; } //substr string substr(size_t pos = 0, size_t len = npos) const { assert(pos >= 0 && pos < _size); size_t n = 0; if (len == npos || pos + len > _size) { n = _size - pos; } else { n = len; } string ret; for (size_t i = 0; i < n; i++) { ret += _str[pos + i]; } return ret; } //其他成员函数 size_t size() const { return _size; } size_t length()const { return _size; } size_t capacity()const { return _capacity; } void clear() { _str[0] = '\0'; _size = 0; } bool empty()const { return _size == 0; } void resize(size_t n) { if (n > _capacity) { reserve(n); } _size = n; _str[_size] = '\0'; } void resize(size_t n, char c) { if (n > _capacity) { reserve(n); } for (size_t i = _size; i < n; i++) { _str[i] = c; } _size = n; _str[_size] = '\0'; } private: char* _str; size_t _size; size_t _capacity; const static size_t npos; }; const size_t HL::string::npos = -1; std::ostream& operator<<(std::ostream& out, const HL::string& str) { //for (int i = 0; i < str.size(); i++) //{ // out << str[i]; //} //return out; for (auto ch : str) { out << ch; } return out; } std::istream& operator>>(std::istream& in, HL::string& str) { char s[128] = { 0 }; char ch; ch = in.get(); while (ch == ' ' || ch == '\n') { ch = in.get(); } str.clear(); int i = 0; while (ch != '\n') { s[i] = ch; i++; if (i == 127) { s[i] = '\0'; str += s; i = 0; } ch = in.get(); } if (i) { str += s; } return in; } };
