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3.5 stringMock implementation of class

//string.h
#pragma once
#include<iostream>
#include<assert.h>
using namespace std;
namespace mystr {
	class string
	{
	public:
		//迭代器, 因为字符串底层内存连续, 所以可以简单的定义成指针
		typedef char* iterator;
		typedef const char* const_iterator;
		//配合范围for循环
		iterator begin() { return _str; }
		iterator end() { return _str + _size; }
		//兼容常量字符串
		const_iterator begin() const { return _str; }
		const_iterator end() const { return _str + _size; }
		//string();
		string(const char* str = "");
		string(const string& s);
		string& operator=(string temp) { swap(temp); return *this; }
		~string() { delete[] _str; _str = nullptr; _size = _capacity = 0; }
		//返回C语言字符数组
		const char* c_str() const { return _str; }
 
		size_t size() const { return _size; }
		char& operator[](size_t pos) { assert(pos < _size); return _str[pos]; }
		const char& operator[](size_t pos) const{ assert(pos < _size); return _str[pos]; }
		//重置大小
		void reserve(size_t n);
 
		void push_back(char ch) { insert(_size, ch); }
		void append(const char* str) { insert(_size, str); }
 
		string& operator+=(char ch) { insert(_size, ch); return *this; }
		string& operator+=(const char* str) { insert(_size, str); return *this; };
 
		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) {
			for (size_t i = pos; i < _size; i++) if (_str[i] == ch) return i;
			return npos;
		}
		size_t find(const char* str, size_t pos = 0) { return strstr(_str + pos, str) - _str; }
 
		void swap(string& s);
		string substr(size_t pos = 0, size_t len = npos);
 
		bool operator<(const string& s) const { return strcmp(_str, s._str) < 0; }
		bool operator>(const string& s) const { return !(*this <= s); }
		bool operator<=(const string& s) const { return !(*this > s); }
		bool operator>=(const string& s) const { return !(*this < s); }
		bool operator==(const string& s) const {return strcmp(_str, s._str) == 0; }
		bool operator!=(const string& s) const { return !(*this == s); }
		void clear() { _str[0] = '0'; _size = 0; }
 
 
	private:
		char* _str;
		size_t _size;
		size_t _capacity;
		//一般static变量的定义要放在类外, 整型是特例
		const static size_t npos = -1;
	};
	void swap(string& s1, string& s2);
	istream& operator>>(istream& ci, string& s);
	ostream& operator<<(ostream& co, string& s);
}
 

//string.cpp
#include "string.h"
namespace mystr {
	string::string(const char* str):_size(strlen(str)) {
		_str = new char[_size + 1];
		_capacity = _size;
		strcpy(_str, str);
	}
	string::string(const string& s) {
		string temp(s._str);
		swap(temp);
	}
	void string::reserve(size_t n) {
		if (_capacity < n) {
			char* temp = new char[n + 1];
			strcpy(temp, _str);
			delete[] _str;
			_str = temp;
			_capacity = n;
		}
	}
	void string::insert(size_t pos, char ch) {
		assert(pos <= _size);
		if (_size == _capacity) {
			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 string::insert(size_t pos, const char* str) {
		assert(pos <= _size);
		size_t len = strlen(str);
		if (_size + len > _capacity) reserve(_size + len);
		size_t end = _size + len;
		while (end > pos + len - 1) _str[end] = _str[end - len], --end;
		memcpy(_str + pos, str, len);
		_size += len;
	}
	void string::erase(size_t pos, size_t len) {
		if (len > _size - pos) _str[pos] = '0', _size = pos;
		else strcpy(_str + pos, _str + pos + len), _size -= len;
	}
	void string::swap(string& s) {
		char* temp = _str;
		_str = s._str;
		s._str = temp;
		std::swap(_size, s._size);
	}
	string string::substr(size_t pos, size_t len) {
		if (len > _size - pos) { string sub(_str + pos); return sub; }
		else {
			string sub;
			sub.reserve(len);
			for (size_t i = pos; i < pos + len; i++) sub += _str[i];
			return sub;
		}
	}
	void swap(string& s1, string& s2){ s1.swap(s2); }
	istream& operator>>(istream& ci, string& s) {
		s.clear();
		char ch = ci.get();
		while (ch != ' ' && ch != 'n') s += ch, ch = ci.get();
		return ci;
	}
	ostream& operator<<(ostream& co, string& s) {
		for (size_t i = 0; i < s.size(); i++) co << s[i];
		return co;
	}
}

//test.cpp
#include "string.h"
namespace mystr {
	void test1() {
		string s1 = "1111";
		string s2 = s1;
		cout << s1.c_str() << endl << s2.c_str() << endl;
		cout << s1.size() << endl;
	}
	void test2() {
		string s1 = "111";
		string s2 = "222222";
		s1 = s2;
		cout << s1.c_str() << endl;
	}
	void test3() {
		string s1 = "111222333";
		for (auto& i : s1) i += 3;
		cout << s1.c_str() << endl;
		const string s2 = "111222333";
		for (auto& i : s2) cout << i;
		cout << endl;
		for (size_t i = 0; i < s1.size(); i++) cout << (s1[i] += 2);
		cout << endl;
	}
	void test4() {
		string s1 = "sadfsf";
		s1.insert(2, '-');
		cout << s1.c_str() << endl;
		s1.insert(0, '-');
		cout << s1.c_str() << endl;
		s1.insert(2, "11111");
		cout << s1.c_str() << endl;
		s1.insert(0, "222222");
		cout << s1.c_str() << endl;
	}
	void test5() {
		string s1 = "asgfidsgf";
		s1.push_back('-');
		cout << s1.c_str() << endl;
		s1.append("=====");
		cout << s1.c_str() << endl;
		s1 += 'w';
		cout << s1.c_str() << endl;
		s1 += "0000";
		cout << s1.c_str() << endl;
		s1.erase(10);
		cout << s1.c_str() << endl;
		s1.erase(7, 100);
		cout << s1.c_str() << endl;
		s1.erase(3, 2);
		cout << s1.c_str() << endl;
		s1.erase(0);
		cout << s1.c_str() << endl;
	}
	void test6() {
		string s1 = "ksjfghks";
		cout << s1.find('h', 2) << endl;
		cout << s1.find("ghk", 2) << endl;
		cout << s1.find("ghksgs", 2) << endl;
	}
	void test7(){
		string s1 = "sggsdsdf";
		string s2 = "sdgfrgdb";
		cout << s1.c_str() << endl;
		cout << s2.c_str() << endl;
		swap(s1, s2);
		cout << s1.c_str() << endl;
		cout << s2.c_str() << endl;
		s1.swap(s2);
		cout << s1.c_str() << endl;
		cout << s2.c_str() << endl;
		string s3 = s1.substr(2, 5);
		cout << s3.c_str() << endl;
	}
	void test8() {
		string s1, s2;
		cin >> s1 >> s2;
		cout << s1 << endl << s2 << endl;
	}
}
int main() {
	mystr::test8();
	return 0;
}