C++ String类
头文件"String.h"
#include <iostream>
#include <assert.h>
using namespace std;
class String
{
public:
String(const char* str = "")
{
int len = strlen(str);
_capacity = len + 1;
_size = len;
_str = new char[_capacity];
strcpy(_str, str);
}
//交换函数
void _Swap(String& s)
{
swap(_str, s._str);
swap(_size, s._size);
swap(_capacity, s._capacity);
}
String(const String& s)
:_str(new char[1]())
{
String tmp = s._str;
_Swap(tmp);
}
//析构函数
~String()
{
if (_str)
{
delete[]_str;
_str = NULL;
}
}
void Display()
{
cout << _str << endl;
}
/********************************************************/
/***********************重载各个运算符*******************/
/********************************************************/
String& operator=(String s)
{
String _Swap(s);
return *this;
}
bool operator>(const String& s)
{
return strcmp(_str, s._str) > 0 ? true : false;
}
bool operator<(const String& s)
{
return strcmp(_str, s._str)>0 ? false : true;
}
bool operator==(const String& s)
{
return strcmp(_str, s._str) == 0 ? true : false;
}
bool operator>=(const String& s)
{
return strcmp(_str, s._str) >= 0 ? true : false;
}
bool operator<=(const String& s)
{
return strcmp(_str, s._str) <= 0 ? true : false;
}
/************************************************************/
/***********************实现String常见函数*******************/
/************************************************************/
//尾插
void PushBack(char ch)
{
_CheckCapacity(_size + 2);
_str[_size++] = ch;
_str[_size] = '\0';
}
//pos位置插入字符ch
void Insert(size_t pos, char ch)
{
assert(pos <= _size);
_CheckCapacity(_size + 2);
int end = _size + 1;
while (end >= pos)
{
_str[end] = _str[end - 1];
--end;
}
_str[pos - 1] = ch;
++_size;
}
/*
int len = 1;
_size += len;
_str = _CheckCapacity();
for (size_t i = _size; i >= pos; i++)
{
_str[i] = _str[i - 1];
}
_str[pos - 1] = ch;
*/
//pos位置插入一个把字符串
void Insert(size_t pos, const char* str)
{
assert(pos <= _size);
size_t strSize = strlen(str);
_CheckCapacity(_size + 1 + strSize);
int end = _size;
while (end >= (int)pos)
{
_str[end + strSize] = _str[end];
--end;
}
while (*str)
{
_str[pos++] = *str++;
}
_size += strSize;
}
char& operator[](size_t index)
{
return _str[index];
}
//Find一个字符
int Find(char ch)
{
for (size_t i = 0; i < _size; i++)
{
if (_str[i] == ch)
{
return i;
}
}
return -1;
}
//Find一个字符串
int Find(const char* str)
{
const char* pscr = _str;
const char* psub = str;
int scrlen = _size;
int sublen = strlen(str);
int scrIndex = 0;
while (scrIndex <= scrlen - sublen)
{
int i = scrIndex;
int j = 0;
while (scrlen > i&&j < sublen&&pscr[i] == psub[j])
{
i++;
j++;
}
if (j == sublen)
{
return scrIndex;
}
scrIndex++;
}
return -1;
}
//删除pos位置后的n个字符
void Erase(size_t pos, size_t n)
{
assert(pos < _size);
for (size_t i = pos; i < _size; i++)
{
_str[i] = _str[i + n];
}
_size -= n;
}
//删除pos位置的字符
void Erase(size_t pos)
{
assert(pos < _size);
for (size_t i = pos; i < _size; i++)
{
_str[i] = _str[i + 1];
}
_size--;
}
private:
//检查指针指向空间的大小并进行扩容
void _CheckCapacity(size_t size)
{
if (size >= _capacity)
{
int newCapacity = size > 2 * _capacity ? size : 2 * _capacity;
_str = (char*)realloc(_str, newCapacity);
_capacity = newCapacity;
}
}
char *_str; //字符串指针
size_t _size; //字符串容量
size_t _capacity; //字符串空间大小
};
//测试
void Test1()
{
String s1("hello world");
s1.Display();
String s2(s1);
s2.Display();
String s3("change world");
s1 = s3;
s1.Display();
}
void Test2()
{
String s1("ello world");
s1.Insert(1, 'h');
s1.Display();
}
void Test3()
{
String s1("hello rld");
char* str = "wo";
s1.Insert(6, str);
s1.Display();
}
void Test4()
{
String s1("hello");
cout << s1[0] << endl;
}
void Test5()
{
String s1("hello world");
cout << s1.Find("ll") << endl;
}
void Test6()
{
String s1("hello world");
s1.Erase(2, 3);
s1.Display();
}
"test.cpp"
#include "String.h"
int main()
{
Test1();
Test2();
Test3();
Test4();
Test5();
Test6();
system("pause");
return 0;
}
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