C++：string的的模拟实现

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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& operatorreturn _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] = '
              14.find函数实现
              ';_size = pos;}else{strcpy(_str + pos, _str + pos + len);_size -= len;}}

              size_t find(char ch, size_t pos);

              size_t find(const char* str, 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 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
               
              17.运算符重载
               
              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;i  
              bool operator(const string& s) const;bool operator=(const string& s) const;bool operator==(const string& s) const;bool operator!=(const string& s) const;
               
              18.>>重载函数和重载函数 
               
              bool string::operatorreturn strcmp(_str, s._str)  
              void string::clear(){_str[0] = '
              for (size_t i = 0; i 
              ';_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] = '';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] = '';str += buff;}return is;}
              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