关于动态开辟　二维空间，　你可以去看我在我的博客里写的一篇文章：
http://blog.bc-cn.net/user1/121/archives/2006/2172.shtml

下面给一个动态开辟一维空间的例子：

#include <iostream>
using namespace std;

int main()
{
int n;
int * p; // to receive the addresse, where a dynamic array allocated
// so that you can work with this dynamic array
// pay attention: here is one dimension array
cout<<"Please enter the number of elements, that you want an one dimension array hat: ";
if(cin>>n)
{
p = new int[n];
// now you have allocated the space for your one dimension array
// p is here the first address of this array
// you can write someting there
// and make some changement
// or display them.

// for example I write something in this array
for(int i = 0; i<n; i++)
{
p[i] = i;
}

// and maybe some statements will be here
// --- some code ---

// and now some code to change this array
// for example inverse
for(int i = 0; i<(n>>1); i++)
{
int temp = p[i];
p[i] = p[n-i-1];
p[n-i-1] = temp;
}

// now you maybe want show this array
for(int i = 0; i<n; i++)
{
cout<<p[i]<<" ";
}
}

// you have done everything with your program, now you want leave.
// Caution: Never forget to free the dynamic allocation
delete [] p;

system("pause");
return 0;
}

...
if(cin>>n)
...
for(int i = 0; i<(n>>1); i++)
...
这俩个是什么意思？cin>>n怎么返回布尔型吗？i<(n>>1)这个也不懂啊

谢谢大家，我得到了一个不错的答案并且上机试验过了，效果不错：
//动态构造并初始化二维数组"array"
void build(void)
{
double **array,size;
label:cout<<"请输入行列式的阶\n";
cin>>size;
if(size>=1&&(int)size==size)
{
array = (double**)malloc(sizeo(doublef*)*size);
for( int i=0; i<size; i++ )
{
array[i] = (double*)malloc(sizeof(double)*size);
}
for( int a=0;a<size;a++)
for(int b=0;b<size;b++)
{
cout<<"请输入第"<<a+1<<"行第"<<b+1<<"列的数\n";
cin>>array[a][b];
}
}
else
{
cout<<"\a输入错误，请重新输入\n";
goto label;
}
}
但是其中两句有些不明白：
array = (double**)malloc(sizeo(doublef*)*size);
array[i] = (double*)malloc(sizeof(double)*size);
哪位高手能解释得详细一些呢？
还有，为什么第二句要用循环语句而第一句不用呢？
麻烦解释一下我真得很想弄明白谢谢！！

这两句应该是申请内存单元的命令吧，用来申请一个动态的空间。

第一句应该是给怎个数组申请空间吧，第二句就应该是给每个成员申请空间。

我的理解是这样的，还请高手指教！！