例如：
#include<iostream>
#include<fstream>
using namespace std;
#define M 3
#define N 2
#define P 2
#define n (M+1)*(N+1)*(P+1)
int main()
{
    int i,j,k,count=0,m=0;
    cout<<M<<"  "<<N<<"  "<<P<<endl;
    cout<<n<<endl;
    int Ap[n+1];
    int a[n][n];
        /*此处为稀疏矩阵的元素确定*/
    for(i=0;i<n;i++)
    {
        for(j=0;j<n;j++)
        {
            cout<<a[i][j]<<" ";
            if(a[i][j]!=0)
                m+=1;
        }
        cout<<endl;
    }
    ofstream outfile1;
    outfile1.open("D:\\2013IBM\\coefficient\\Array of A\\a[i][j].txt",ios::out);
    for(i=0;i<n;i++)
    {
        for(j=0;j<n;j++)
        {
            outfile1<<a[i][j]<<" ";
        }
        outfile1<<endl;
    }
    outfile1<<endl;
    outfile1.close();

    int Ai[m];  //数组大小m这样定义不正确，怎么办？m为矩阵a中的非零个数个数
    double Ax[m];
    Ap[0]=0;
    for(j=0;j<n;j++)
    {
        for(i=0;i<n;i++)
        {
            if(a[i][j]!=0)
            {
                count+=1;
                Ai[n-1]=i;
                Ax[n-1]=a[i][j];
            }
            Ap[j+1]=count;
        }
    }
    for(j=0;j<n+1;j++)
    {
        cout<<Ap[j]<<" ";
    }
    cout<<endl;
    ofstream outfile2;
    outfile2.open("D:\\2013IBM\\coefficient\\Array of A\\Ap.txt",ios::out);
    for(j=0;j<n+1;j++)
    {
        outfile2<<Ap[j]<<" ";
    }
    outfile2<<endl;
    outfile2.close();

    for(j=0;j<count;j++)
    {
        cout<<Ai[j]<<" ";
    }
    cout<<endl;
    ofstream outfile3;
    outfile3.open("D:\\2013IBM\\coefficient\\Array of A\\Ai.txt",ios::out);
    for(j=0;j<count;j++)
    {
        outfile3<<Ai[j]<<" ";
    }
    outfile3<<endl;
    outfile3.close();

    for(j=0;j<count;j++)
    {
        cout<<Ax[j]<<" ";
    }
    cout<<endl;
    ofstream outfile4;
    outfile4.open("D:\\2013IBM\\coefficient\\Array of A\\Ax.txt",ios::out);
    for(j=0;j<count;j++)
    {
        outfile4<<Ax[j]<<" ";
    }
    outfile4<<endl;
    outfile4.close();
}

具体点，动态内存分配的话，也需要在定义一维数组时指定一个数组大小才可以？如果不指定数组大小可以不？

这是C++啊，不是C语言！

容器这一章我还不怎么会！

这没啥影响的，大家都能看到！呵呵，好吧！我了解了！