各位亲兄弟们c语言这一题怎么弄啊

供参考：

#include <stdio.h>
#include <ctype.h>
int main()
{
    char a[128], b[128], c[128];
    int i = 0, j = 0, k = 0;
    gets(a);
    while (a[i])
    {
        if (isdigit(a[i]))
            b[j++] = a[i++];
        else if (iswalpha(a[i]))
            c[k++] = a[i++];
    }
    b[j] = '\0'; c[k] = '\0';
    puts(b);
    puts(c);
    return 0;
}