string.h
声明了一个空间域用来声明string类，这是为了避免和std标准命名空间里的string冲突
#define _CRT_SECURE_NO_WARNINGS 1 #include<assert.h> #include<stdio.h> #include<iostream> #include<string.h> namespace bit { class string { public: typedef char* iterator; typedef const char* const_iterator; public: string(const char* str = ""); string(const string& s); string& operator=(const string& s); ~string(); // // iterator iterator begin(); iterator end(); const iterator begin()const; const iterator end() const; / // modify void push_back(char c); string& operator+=(char c); void append(const char* str); string& operator+=(const char* str); void clear(); void swap(string& s); const char* c_str()const; / // capacity size_t size()const; size_t capacity()const; bool empty()const; void resize(size_t n, char c = '\0'); void reserve(size_t n); / // access char& operator[](size_t index); const char& operator[](size_t index)const; / //relational operators bool operator<(const string& s); bool operator<=(const string& s); bool operator>(const string& s); bool operator>=(const string& s); bool operator==(const string& s); bool operator!=(const string& s); // 返回c在string中第一次出现的位置 int find(char c, size_t pos = 0) const; // 返回子串s在string中第一次出现的位置 int find(const char* s, size_t pos = 0) const; // 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); string& insert(size_t pos, const char* str); // 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, size_t len); private: char* _str; size_t _capacity; size_t _size; }; std::ostream& operator<<(std::ostream& _cout, const bit::string& s); std::istream& operator>>(std::istream& _cin, bit::string& s); std::istream& getline(std::istream& _cin, bit::string& s); };
string.cpp
定义string类中的函数声明以及操作符重载，其中输入输出流的重载是容易搞错的地方
#define _CRT_SECURE_NO_WARNINGS 1 #include"string.h" bit::string::string(const char* str) :_size(strlen(str)){ _str = new char[_size+1]; strcpy(_str, str); _capacity = _size; } bit::string::string(const string& s) { _str = new char[s._capacity + 1]; strcpy(_str, s._str); _size = s._size; _capacity = s._capacity; } bit::string& bit::string::operator=(const string& s) { char* temp = new char[s._capacity+1]; strcpy(temp, s._str); delete[] _str; _capacity = s._capacity; _size = s._size; _str = temp; return *this; } bit::string::~string() { delete[] _str; _capacity = 0; _size = 0; } // iterator //迭代器 bit::string::iterator bit::string::begin() { return _str; } bit::string::iterator bit::string::end() { return _str + _size; } const bit::string::iterator bit::string::begin()const { return _str; } const bit::string::iterator bit::string::end() const{ return _str + _size; } / // 增加字符函数 void bit::string::push_back(char c) { if (_size == _capacity) { reserve(_capacity ==0?4:_capacity*2); } _str[_size++] = c; _str[_size] = '\0'; } bit::string& bit::string::operator+=(char c) { (*this).push_back(c); return *this; } void bit::string::append(const char* str) { size_t n = strlen(str); for (int i = 0; i < n; i++)(*this).push_back(str[i]); } bit::string& bit::string::operator+=(const char* str) { append(str); return *(this); } void bit::string::clear() { _size = 0; _str[_size] = '\0'; } void bit::string::swap(bit::string& s) { std::swap(s._str, _str); std::swap(s._size, _size); std::swap(s._capacity, _capacity); } const char* bit::string::c_str()const { return _str; } / // capacity //容量修改有关函数重载 size_t bit::string::size()const { return _size; } size_t bit::string::capacity()const { return _capacity; } bool bit::string::empty()const { return _size == 0; } void bit::string::resize(size_t n, char c ) { 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'; _capacity = n; _size = n; } } void bit::string::reserve(size_t n) { if (n > _capacity) { char* temp = new char[n + 1]; strcpy(temp, _str); delete[] _str; _str = temp; _str[_size] = '\0'; _capacity = n; } } // access //下标访问 char& bit::string::operator[](size_t index) { assert(index >= 0 && index < _size); return _str[index]; } const char& bit::string::operator[](size_t index)const { assert(index >= 0 && index < _size); return _str[index]; } //relational operators //比较操作符重载 bool bit::string::operator<(const bit::string& s) { int f = strcmp(_str, s._str); return f< 0; } bool bit::string::operator<=(const bit::string& s) { int f = strcmp(_str, s._str); return f <= 0; } bool bit::string::operator>(const bit::string& s) { int f = strcmp(_str, s._str); return f >0 ; } bool bit::string::operator>=(const bit::string& s) { int f = strcmp(_str, s._str); return f >= 0; } bool bit::string::operator==(const bit::string& s) { int f = strcmp(_str, s._str); return f == 0; } bool bit::string::operator!=(const bit::string& s) { int f = strcmp(_str, s._str); return f != 0; } // 返回c在string中第一次出现的位置 int bit::string::find(char c, size_t pos ) const { assert(pos >= 0 && pos < _size); for (size_t i = pos; i < _size; i++) { if (_str[i] == c)return i; } return -1; } // 返回子串s在string中第一次出现的位置 int bit::string::find(const char* s, size_t pos ) const { assert(pos >= 0 && pos < _size); const char* t= strstr(_str + pos, s); if (t == NULL)return -1; return t - _str; } // 在pos位置上插入字符c/字符串str，并返回该字符的位置 bit::string& bit::string::insert(size_t pos, char c) { assert(pos <=_size); reserve(_capacity + 1); //_str[_size] = '\0'; size_t end = _size+1; while (end >= pos) { _str[end] = _str[end-1]; end--; } _str[pos] = c; _size++; return *this; } // bit::string & bit::string::insert(size_t pos, const char* str) { assert(pos <= _size); size_t len = strlen(str); reserve(_capacity + len); size_t end = _size + len; while (end >= pos+len) { _str[end] = _str[end - len]; end--; } strncpy(_str + pos, str, len); //size_t cnt = 0; /*for (size_t i = pos; i < pos + len; i++) { _str[i] = str[cnt++]; }*/ _size += len; _str[_size] = '\0'; return *this; } // // // 删除pos位置上的元素，并返回该元素的下一个位置 // bit::string& bit::string::erase(size_t pos, size_t len) { assert(pos < _size); if (len >= _size - pos)len = _size - pos; size_t t = pos + len; strncpy(_str + pos, _str + t,len); _size--; _str[_size] = '\0'; return *this; } std::ostream& bit::operator<<(std::ostream& _cout, const bit::string& s) { for (auto it : s) { _cout << it; } return _cout; } //std::istream& bit::operator>>(std::istream& _cin, bit::string& s) { // s.clear(); // char ch; // ch = _cin.get(); // s.reserve(128); // while (ch != '\n' && ch != ' ') { // s += ch; // ch = _cin.get(); // } // return _cin; //} std::istream& bit::operator>>(std::istream& _cin, bit::string& s) { s.clear(); char ch; ch = _cin.get(); char buff[128]; size_t cnt = 0; while (ch != '\n' && ch != ' ') { buff[cnt++] = ch; if (cnt == 127) { s += buff; cnt = 0; } ch = _cin.get(); } if (cnt != 0) { buff[cnt] = '\0'; s += buff; //s[(s.size())] = '\0'; cnt = 0; } return _cin; } std::istream& bit::getline(std::istream& _cin, bit::string& s) { s.clear(); char ch; ch = _cin.get(); char buff[128]; size_t cnt = 0; while (ch != '\n' ) { buff[cnt++] = ch; if (cnt == 127) { s += buff; cnt = 0; } ch = _cin.get(); } if (cnt != 0) { buff[cnt] = '\0'; s += buff; //s[(s.size())] = '\0'; cnt = 0; } return _cin; }
