大整数加法

【关键在于怎么把大数读入数组（用一个char型变量做辅助）】

#include <stdio.h>
#include <string.h>
#define M 10
#define N 1000
void add(int *a,int *b,int *c)//加法
{
    int i,carry=0;
    for (i=N-1;i>=0;i--)
    {
        c[i]=a[i]+b[i]+carry;
        if (c[i]>=M)
        {
            c[i]-=M;
            carry = 1;
        }
        else
        {
            carry = 0;
        }
    }
}
void con(int *a,int *c)//转换
{
    int i,j;
    i=0;
    while (c[i]==0)
        i++;
    j=999;
    while (i<=999)
        a[j--]=c[i++];

}
void main()
{
    int a[1000],b[1000],c[1000],i;
    char ch;
    memset(a,0,sizeof(a));
    memset(b,0,sizeof(b));

    i=999;
    memset(c,0,sizeof(c));
    while ((ch=getchar())!='\n')
        c[i--]=ch-48;
    con(a,c);
    i=999;
    memset(c,0,sizeof(c));
    while ((ch=getchar())!='\n')
        c[i--]=ch-48;    
    con(b,c);
    memset(c,0,sizeof(c));
    add(a,b,c);
    i=0;
    while (c[i]==0)
        i++;
    while (i<=999)
        printf("%d",c[i++]);
    printf("\n");
}