算法训练 进制转换

#include <stdio.h>
char Stack[18];
short top = -1;
short IsEmpty()
{
    if(top == -1)
        return 0;
    return 1;
}
void push(char e)
{
    Stack[++top] = e;
}
void pop(char* e)
{
    *e = Stack[top--];
}
int main()
{
    int N,temp,R;    
    char e;
    scanf("%d%d",&N,&R);
    temp = N;
    if(-R <= 9)
    {
        while(temp)
        {
            if(temp%R >= 0)    
            {
                push(‘0‘+temp%R);
                temp /= R;
            }
            else{
                push(‘0‘ + (temp - R*(temp/R+1)));
                temp = temp/R + 1;
            }
        }
    }
    else{
        while(temp)
        {
            if(temp%R >=0)
            {
                if(temp%R <= 9)
                {
                    push(‘0‘+temp%R);
                }
                else{//当R=-20，余数可能为10
                    push(‘A‘+ (temp%R-10));
                }
                temp /= R;
            }
            else{
                if(-R + temp%R <= 9)//判断差值
                    push(‘0‘ + (temp - R*(temp/R+1)));
                else
                    push(‘A‘ + (-R + temp%R - 10));
                temp = temp/R + 1;
            }
        }
    }
    printf("%d=",N);
    while(IsEmpty())
    {
        pop(&e);
        putchar(e);
    }
    printf("(base%d)\n",R);
    return 0;
}