C++自定义Vector模板

  C++的vector函数，当数据量到达一定程度，清空时就会花费很多时间。打算自己写一个内存管理器，并写一个可变长的数组。下面是我的vector代码：

MyVector.h:

#ifndef __MY_VECTOR_H
#define __MY_VECTOR_H

#include <stdio.h>

#define SafeDelete(_x)		{ if (_x) { delete (_x); (_x) = NULL; } }
#define SafeDeleteArray(_x)	{ if (_x) { delete [] (_x); (_x) = NULL; } }

template <typename T>
class MyVector{
public:
	//默认构造函数
	MyVector(){
		this->length=0;
		this->maxlength=10;
		this->data=new T[this->maxlength];
		for (unsigned i=0;i<this->maxlength;i++)
		{
			this->data[i]=NULL;
		}
	};
	//初始化长度
	MyVector(unsigned initLength){
		if (initLength<5)
		{
			printf("warning: vector init_length must more than 5.\n");
			initLength=5;
		}
		this->length=0;
		this->maxlength=initLength;
		this->data=new T[this->maxlength];
		for (unsigned i=0;i<this->maxlength;i++)
		{
			this->data[i]=NULL;
		}
	};
	//拷贝构造函数
	MyVector(const MyVector& v){
		this->length=v.length;
		this->maxlength=v.maxlength;
		this->data=new T[this->maxlength];
		for (unsigned i=0;i<this->maxlength;i++)
		{
			this->data[i]=v.data[i];
		}
	};
	~MyVector(){
		this->length=0;
		this->maxlength=0;
		SafeDeleteArray(this->data);
	};
	//插入一个元素到最后
	void insert(T element){
		if (this->length>=this->maxlength)
		{
			unsigned i;
			T* dataTemp=new T[this->maxlength*2];
			for (i=0;i<this->maxlength;i++)
			{
				dataTemp[i]=this->data[i];
			}
			this->maxlength=this->maxlength*2;
			for (i=0;i<this->maxlength;i++)
			{
				dataTemp[i]=NULL;
			}
			SafeDeleteArray(this->data);
			this->data=dataTemp;
		}
		this->data[this->length]=element;
		this->length++;
	};
	//清空vector
	void clear(){
		SafeDeleteArray(this->data);
		this->length=0;
		this->maxlength=10;
		this->data=new T[this->maxlength];
		for (unsigned i=0;i<this->maxlength;i++)
		{
			this->data[i]=NULL;
		}
	};
	//获得下标为i的对象
	T get(unsigned i){
		if (i>=this->length)
		{
			return NULL;
		}
		return this->data[i];
	};
	//设置下标为i的对象，返回原来的对象
	T set(unsigned i, T element){
		if (i>=this->maxlength)
		{
			unsigned j;
			T* dataTemp=new T[2*i];
			for (j=0;j<this->maxlength;j++)
			{
				dataTemp[j]=this->data[j];
			}
			this->maxlength=2*i;
			for (;j<this->maxlength;j++)
			{
				dataTemp[j]=NULL;
			}
			SafeDeleteArray(this->data);
			this->data=dataTemp;
		}
		T olddata=this->data[i];
		this->data[i]=element;
		if (this->length<i+1)
		{
			this->length=i+1;
		}
		return olddata;
	};
	//获得vector元素个数
	unsigned size(){
		return this->length;
	};
	//重载[]操作符
	T& operator[](unsigned i){
		if (i>=this->length)
		{
			printf("error: vector is out of vector.\n");
			exit(1);
		}
		return this->data[i];
	};
	//重载=操作符
	MyVector& operator=(const MyVector & v){
		this->length=v.length;
		this->maxlength=v.maxlength;
		SafeDeleteArray(this->data);
		this->data=new T[this->maxlength];
		for (unsigned i=0;i<this->maxlength;i++)
		{
			this->data[i]=v.data[i];
		}
		return *this;
	};

private:
	T* data;									//存储数据的数组
	unsigned length;							//数组元素
	unsigned maxlength;							//最大可存储空间
};
#endif

#include <stdio.h>
#include <stdlib.h>
#include "MyVector.h"

int main(){
	MyVector<int> v1;
	v1.insert(3);
	MyVector<int> v2;
	v2=v1;
	printf("%d\n",v1[0]);
	printf("%d\n",v2[0]);
	system("PAUSE");
	return 0;
}

    注意到模板类的写法，最好将类的成员函数在类声明时定义。否则可能会遇到一些编译错误。具体看http://blog.csdn.net/jfkidear/article/details/7888167

    以上的MyVector是一个简单版本的。需要说明的一点是，若MyVector<int> v2=v1，调用的是拷贝构造函数。若MyVector<int> v2; v2=v1; 则调用的是=重载函数。因此，=操作符必须重写，拷贝构造函数要重写。

    转自：康瑞的部落 ? C++自定义Vector模板

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