String类

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String.h

#pragma once#include<iostream>using namespace std;#include<assert.h>class String{public:    String(char *str = "")//构造函数    {        _size = strlen(str);        _capa = _size;        _str = new char[_capa + 1];        strcpy(_str, str);    }    void Swap(String& s)    {        swap(_str, s._str);        swap(_size, s._size);        swap(_capa, s._capa);    }    String(const String& s)//拷贝构造        :_str(NULL)        , _size(0)        , _capa(0)    {        String tmp(s._str);        Swap(tmp);    }    ~String()//析构    {        if (_str)        {            delete[] _str;            _str = NULL;            _size = _capa = 0;        }    }    String& operator=(String s)//赋值运算符=重载    {        Swap(s);        return *this;    }    char *GetStr()//获取字符串    {        return _str;    }    size_t size()//获取大小    {        return _size;    }    char& operator[](size_t pos)//[]重载        //1.出了作用域，_str还在，所以用&        //2.可读可写    {        assert(pos<_size);        return _str[pos];    }    void Expand(size_t n)//扩容    {        if (n > _capa)        {            _str = (char*)realloc(_str, n + 1);            assert(_str);            _capa = n;        }    }    void PushBack(char ch)//尾插一个字符    {        if (_size == _capa)        {            Expand(_capa*2);        }        _str[_size] = ch;        ++_size;        _str[_size] = '\0';    }    void PushBack(const char* str)//尾插一个字符串    {        size_t len = strlen(str);        if (len + _size > _capa)        {            Expand(len + _size);        }        strcpy(_str+_size, str);    }    void PopBack()//尾删一个字符    {        assert(_size);        _str[--_size] = '\0';    }    void Insert(size_t pos, char ch)//指定位置插入一个字符    {        if (_size == _capa)        {            Expand(_capa * 2);        }        int end = _size;        while (end >= (int)pos)        {            _str[end + 1] = _str[end];            --end;        }        _str[pos] = ch;        ++_size;    }    void Insert(size_t pos, const char *str)//指定位置插入一个字符串    {        size_t len = strlen(str);        if (len + _size > _capa)        {            Expand(len + _size);        }        int end = _size;        while (end >= (int)pos)        {            _str[end + len] = _str[end];            --end;        }        while (*str)        {            _str[pos++] = *str++;        }        _size += len;    }    void Erase(size_t pos, size_t count)//删除指定位置的count个字符    {        if (pos + count >= _size - 1)        {            _str[pos] = '\0';            _size = pos;        }        else        {            strcpy(_str + pos, _str + pos + count);            _size -= count;        }    }    int Find(char ch) const//查找一个字符    {        for (size_t i = 0; i < _size; i++)        {            if (_str[i] == ch)            {                return i;            }        }        return -1;    }    int Find(const char*str) const//查找n个字符    {        assert(str);        const char* srcstr = _str;//原字符串        const char* substr = str;//要寻找的子串        size_t srcindex = 0;        size_t subindex = 0;        size_t sublen = strlen(substr);        while (srcindex < _size)        {            size_t matchindex = srcindex;            while (srcstr[matchindex] == substr[subindex])            {                ++matchindex;                ++subindex;                if (subindex == sublen)                {                    return srcindex;                }            }            subindex = 0;            srcindex++;        }        return -1;    }    //赋值运算符重载    inline bool operator<(const String& s) const    {        size_t i = 0;        for (; i < _size && i < s._size; i++)        {            if (_str[i] > s._str[i])            {                return false;            }        }        if (i == _size&&i < s._size)        {            return true;        }        else        {            return false;        }    }    inline bool operator==(const String& s) const    {        size_t i = 0;        for (; i < _size && i < s._size; i++)        {            if (_str[i] != s._str[i])            {                return false;            }        }        if (i == _size&&i == s._size)        {            return true;        }        else        {            return false;        }    }    inline bool operator<=(const String& s) const    {        return *this < s || *this == s;    }    inline bool operator>(const String& s) const    {        return !(*this <= s);    }    inline bool operator>=(const String& s) const    {        return *this > s || *this == s;    }    inline bool operator!=(const String& s) const    {        return !(*this == s);    }private:    char *_str;    size_t _size;//大小    size_t _capa;//容量};void TestString(){    String s1("hello");    String s2(s1);    s1.PushBack(' ');    s1.PushBack('w');    s1.PushBack('o');    s1.PushBack('r');    s1.PushBack('l');    s1.PushBack('d');    cout << s1.GetStr() << endl;    s2.PushBack(" world!");    cout << s2.GetStr() << endl;    String s3("hellworld?");    String s4(s3);    s3.Insert(4, ' ');    s3.Insert(4, 'o');    cout << s3.GetStr() << endl;    s4.Insert(4, ' ');    s4.Insert(4, 'o');    cout << s4.GetStr() << endl;    String s5("world");    s5.Insert(0, "hello ");    cout << s5.GetStr() << endl;    String s6("hello world?");    String s7(s6);    s6.Erase(5, 6);    cout << s6.GetStr() << endl;    s7.Erase(5, 20);    cout << s7.GetStr() << endl;    String s8("aabcdaabbbaa");    cout << s8.Find("aabb") << endl;    cout << s8.Find("aabx") << endl;    String s9("hello world!");    s9.PopBack();    cout << s9.GetStr() << endl;}

测试部分

#include"String.h"int main(){    TestString();    system("pause");}

程序测试结果：
这里写图片描述

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