程序代码：

// Note:Your choice is C++ IDE
#include <iostream>
#include <time.h>
#include <stdlib.h>
using namespace std;

int fun(int n)
{
    int nSum = 1;
   
    for(int i = 0; i != n; ++i)
    {
        nSum *= 10;    
    }
   
    return nSum;
}

int main()
{
    while(1)
    {
        cout<<"请输入位数:";
        int nSize;
        cin>>nSize;
       
        if(nSize <= 0)
        {
            exit(0);
        }
       
        srand(time(NULL));
       
        int m;
        int n;
       
        if(nSize == 1)
        {
            m = rand()%10;
            n = rand()%10;   
        }
        else
        {
            m = fun(nSize - 1) + rand()%( 9*fun(nSize - 1) );
            n = fun(nSize - 1) + rand()%( 9*fun(nSize - 1) );
        }
       
        cout<<m<<'+'<<n<<'='<<m+n<<endl;
    }
   
    return 0;
}