#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PROG_VERSION    "v1.0"
#define AUTHOR_NAME     "your_name"
#define CLASS           "your_class"
#define FINISH_DATE     "2012.12.13"

int conv(const char *num, int radix)
{
    int p = 1, n = 0;
    int i;
    for(i = strlen(num) - 1; i >= 0; i--)
    {
        n += (num[i] - '0') * p;
        p *= radix;
    }
    return n;
}

void write(int dec, int radix)
{
    int arr[1000], p;
    p = 0;
    while(dec) {
        arr[p++] = dec % radix;
        dec /= radix;
    }
    while(--p >= 0) putchar((arr[p] < 10) ? (arr[p] + '0') : (arr[p] - 10 + 'A'));
    printf("\n");
}

int main()
{
    char str[100], num[100];
    const int func[6][2] = {{10, 2}, {10, 16}, {10, 8}, {2, 10}, {2, 8}, {2, 16}};
   
    printf("Number Converter %s\n", PROG_VERSION);
    printf("%s @ Class %s, %s\n\n", AUTHOR_NAME, CLASS, FINISH_DATE);
   
    while(true) {
        printf("A. 10进制 ->  2进制\n");
        printf("B. 10进制 -> 16进制\n");
        printf("C. 10进制 ->  8进制\n");
        printf("D.  2进制 -> 10进制\n");
        printf("E.  2进制 ->  8进制\n");
        printf("F.  2进制 -> 16进制\n");
        printf("Your choice: ");
        scanf("%s", str);
        getchar();
        if(*str >= 'A' && *str <= 'F') {
            printf("Number: ");
            scanf("%s", num);
            getchar();
            write(conv(num, func[*str - 'A'][0]), func[*str - 'A'][1]);
        } else {
            printf("Incorrect choice.\n");
        }
        printf("\n");
    }
}