怎样用vc++5.0中的类创建一个二维动态数组
编号：QA002474
建立日期: 2000年1月23日 最后修改日期：2002年6月5日
所属类别：
赵星:
编程工具: vc++5.0
操作系统: win98
问题: 我由于不知要建数组的大小，希望创建一个二维动态数组，请问怎样用vc++5.0中的类如CArray, 创建一个二维动态数组？
回答:
假设二维数组的元素是 Class T, 则可生成一个 template <class T>的动态二维数组。 必须注意以下几点。
1，必须自定义一个以行数、列数为参数的构造函数。
2，必须自定义析构函数，以保证在析构该二维数组类的同时确实清除所有元素的内存空间。
3，为了使用方便，建议重载括号操作符，实现对元素的引用。
4, 建议查看 CArray 的源码，以确认每个步骤。
下面是基本框架：
头文件：
#include <afxtempl.h>
template <class T> class C2dArray: public CArray<CArray<T, T&>, CArray<T,T&>&>
{
protected:
short row, col;
public:
C2dArray();
C2dArray(short row, short col);
SetSize(short row, short col);
virtual ~C2dArray();
T& operator () (short row, short col); // 重载括号操作
};
template <class T> inline T& C2dArray<T>::operator () (short row, short col)
{
.....
}
CPP 文件：
template <class T> C2dArray<T>::C2dArray()
{ SetSize(0,0);}
template <class T> C2dArray<T>::C2dArray(short row, short col)
{ SetSize(row,col);}
template <class T> C2dArray<T>::SetSize(short row, short col)
{
.....
}
template <class T> C2dArray<T>::~C2dArray()
{
...
}
C++ 的 new 操作直接支持多维数组的申请。详情可参考 new 的联机帮助。
new 支持多维数组的申请, 但仅对最高维是动态的，较低维的各维的长度必须是常数。本人编写了两个动态多维数组申请和释放的函数。 分别为mnew 和 mdelete. 代码如下。注意，其中可变参数列表中的数必须是长整型的。第二个参数 dimention 表示的是要申请的数组的维数，后面就是各维所对应的长度。
char * mnew (unsigned long typesize, unsigned short dimention, ...) /*=============================================================================
by Kan ZENG, 2000.02.16. tested on 2000.02.16
mnew and mdelete are couple of routines to deal with allocing and freeing
the memory for multi-dimention array.
para:
typesize -- the size in byte of one element
dimention - the number of dimention
... - the variational argument list. each one MUST BE long interger.
The further right, the lower the dimention is.
p - the pointer which was alloced by mnew
Return:
mnew return the first address of alloced memory block if successful or NULL
if fail.
Usage:
if a double type 3D dynamical array is required, the method to using mnew as
following:
double ***myarray =
(double ***) mnew(sizeof(double),3, (long)n3, (long)n2, (long)n1);
After that, you can refer the element as usual:
e.g. myarray[4][2][5]=45.77;
=============================================================================*/
{
va_list vl;
long i, j;
long prdt1, prdt2;
long *dim;
char *res;
if (dimention <1) return NULL;
dim= new long[dimention];
// dimention is the last argument specified; all
// others must be accessed using the variable-
// argument macros.
va_start( vl, dimention);
// Step through the list.
for(i=dimention-1; i>=0; i--)
dim[i]=va_arg( vl, long );
va_end( vl );
if (dimention==1) {
res = new char[dim[0]];
delete[] dim;
return res;
}
prdt1=dim[1]; prdt2=dim[0]*dim[1];
for(i=2; i ++prdt1 *= dim[i];
prdt2 *= dim[i];
}
if ((res=new char[prdt1*sizeof(void *)+prdt2*typesize])==NULL) {
delete[] dim;
return NULL;
}
char *p;
void **q2, **p1, **p2;
p = res+prdt1*sizeof(void *) ;
q2 = (void **)p;
prdt2 /= dim[0];
q2 -= prdt2;
p2 = q2;
for(j=0; j *p2=p;
p2++;
p+=dim[0]*typesize;
}
for(i=1; i<(dimention-1); i++) {
p1=q2;
prdt2 /= dim[i];
q2 -= prdt2;
p2 = q2;
for(j=0; j *p2=p1;
p2++; p1+=dim[i];
}
}
delete[] dim;
return res;
}
void mdelete(void * p)
{
if (p==NULL) return;
delete[] (char *)p;
p=NULL;
}
kaffir的意见：
#define matrix_allocate(matrix, width, height, TYPE) {\
matrix = new TYPE* [height];\
for(int _i = 0; _i < height; _i++)\
matrix[_i] = new TYPE[width];\
}
#define matrix_delete(matrix, width, height){\
for(int _i = 0; _i < height; _i++)\
delete [] matrix[_i];\
delete [] matrix;\
matrix = 0;\
}
用这两个宏吧 很爽的 hoho~~
此问题由曾侃回答。
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