C语言：大数相乘.

#include<stdio.h>
#include<string.h>
#define N 200
void mul(char a[], int n, char b[], int m)
{
int s
= {0}, i=N-1, p=0;
int l, j;
for( ; n>=0; n--)
{
for(j=i, l=m; l>=0; j--, l--)
{
s[j] = s[j] + (a
-'0')*(b[l]-'0')+p;
p = s[j]/10;
s[j] = s[j]%10;
}
while(p)
{
s[j--] = p%10;
p = p/10;
}
i--;
}
for(i=j+1; i<N; i++)
printf("%d", s[i]);
printf("\n");
}

int main()
{
char a[20], b[20];
int n, m;
printf("\nPlease input the first  number: ");
gets(a);
n = strlen(a)-1;
printf("\nPlease input the second number: ");
gets(b);
m = strlen(b)-1;
printf("\nThe two  numbers  multibly is: ");
mul(a, n, b, m);
return 0;
}