#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<assert.h>
using namespace std;
class String
{
public:
char* GetStr()
{
return _str;
}
char& operator[] (const size_t pos)
{
char* cur = _str;
cur = cur + pos + 1;
return *cur;
}
void PushBack(const char ch)
{
char* p = new char[_capacity + 1];
strcpy(p, _str);
_str = p;
_str[_size++] = ch;
_str[_size] = ‘\0‘;
_capacity = _size + 1;
}
void PopBack()
{
_str[_size - 1] = _str[_size];
char* p = new char[_capacity - 1];
strcpy(p, _str);
_str = p;
}
void Insert(size_t pos,const char ch)
{
char* p = new char[_capacity + 1];
strcpy(p, _str);
_str = p;
int count = _size - pos + 2;// count 为移动次数
int i = _size;//移动的元素位置
while (count--)//把pos位置及pos后面的 字符 集体向后移一位
{
_str[i + 1] = _str[i];
i--;
}
_str[pos - 1] = ch;
_size++;
_capacity = _size + 1;
}
void Insert(size_t pos, const char* s)
{
int len = strlen(s);
char* p = new char[_capacity + len];
strcpy(p, _str);
_str = p;
//移动原字符串 空出来空间给待插入的字符串
int moveCount = _size - pos + 2 + (len - 1);// moveCount 为移动次数
int i = _size;// i 为移动的元素位置
while (moveCount--)//把pos位置及pos后面的 字符 集体向后移一位
{
_str[i + len] = _str[i];
i--;
}
//插入待插入的字符串
int insertCount = len; // insertCount 为字符插入次数
int posSource = pos;// posSource 为原字符串的下标
int posDest = 0;// posDest 为待插入的字符串s的下标
while (insertCount--)
{
_str[posSource - 1] = s[posDest];
posSource++;
posDest++;
}
_size += len;
_capacity = _size + 1;
}
public:
String& operator+= (const String& str)
{
char* p = new char[this->_size + str._capacity];
//拷贝原字符串
strcpy(p, _str);
_str = p;
//拷贝str的字符串
Insert(_size + 1, str._str);
return *this;
}
String& operator+= (const char* str)
{
int len = strlen(str);
char* p = new char[_capacity + len];
//拷贝原字符串
strcpy(p, _str);
_str = p;
//拷贝str字符串
Insert(_size + 1, str);
return *this;
}
String& operator+= (char c)
{
char* p = new char[_capacity + 1];
strcpy(p, _str);
_str = p;
Insert(_size + 1, c);
return *this;
}
void my_Swap(String& str)
{
swap(_str, str._str);
swap(_size, str._size);
_capacity = _size + 1;
str._capacity = str._size + 1;
}
public:
String(char* str = "")
:_str(_New())
{
assert(_str);//检测分配空间是否成功
strcpy(_str, str);
_size = strlen(str);
_capacity = _size + 1;
}
String(String& s)
:_str(_New())
{
assert(_str);
strcpy(_str, s._str);
_size = strlen(s._str);
_capacity = _size + 1;
}
~String()
{
if (_str != NULL)
{
delete[] _str;
}
}
String& operator=(const String& s)
{
_str = _New();
assert(_str);
strcpy(_str, s._str);
_size = strlen(s._str);
_capacity = _size + 1;
return *this;
}
private:
char* _New()
{
char *p = new char[sizeof(String)+1];
return p;
}
private:
char* _str;
int _size;
int _capacity;
};
//test 构造函数 拷贝构造函数 赋值操作符重载 []操作符重载
void test1()
{
String s1("abcd");
cout << s1.GetStr() << endl;
String s2 = s1;
cout << s2.GetStr() << endl;
String s3;
s3 = s2;
cout << s3.GetStr() << endl;
cout << s3[1] << endl;
}
//test PushBack PopBack
//Insert(size_t pos,char ch)
//Insert(size_t pos,char* s)
void test2()
{
String s1("abcd");
cout << s1.GetStr() << endl;
s1.PushBack(‘e‘);
cout << s1.GetStr() << endl;
s1.PopBack();
cout << s1.GetStr() << endl;
s1.Insert(2, ‘m‘);
s1.Insert(2, ‘n‘);
cout << s1.GetStr() << endl;
s1.Insert(2, "change");
cout << s1.GetStr() << endl;
}
void test3()
{
String firstname("tan");
String secondname("xiaohui");
firstname += secondname;
cout << firstname.GetStr() << endl;
firstname += " is superman";
cout << firstname.GetStr() << endl;
firstname += ‘!‘;
cout << firstname.GetStr() << endl;
firstname.my_Swap(secondname);
cout << firstname.GetStr() << endl;
cout << secondname.GetStr() << endl;
}
int main()
{
//test1();
//test2();
test3();
system("pause");
return 0;
}
本文出自 “水仙花” 博客，请务必保留此出处http://10704527.blog.51cto.com/10694527/1719271
模仿实现C++库函数----String 类----用 深拷贝 实现
原文：http://10704527.blog.51cto.com/10694527/1719271