进制转换

#include <stdio.h>
#include <stdlib.h>
#define N 33
void num (int n, int r, char a[]);
int main()
{
    char a[N];
    int n,r;
    while (scanf ("%d%d", &n, &r)!=EOF)
    {
        num(n, r, a);
    }
    return 0;
}
void num (int n, int r, char a[])
{
    int i = 0;
    if (n<0)
    {
        n = -n;
        printf("-");
    }
    while (n>0)
    {
        a[i]=n%r;
        if (a[i]>=10)
            a[i]=‘A‘+a[i]-10;
        n = n/r;
        i++;
    }
    a[i] = ‘\0‘;
    for ( i = i-1; i>=0; i--)
    {
        if(a[i]>=‘A‘ && a[i]<=‘Z‘)
            printf("%c", a[i]);
        else
            printf ("%d", a[i]);
    }
    printf ("\n");

}