C language (10进制转2，8，16进制)

#import 
#import 

void tran(int num, int k) {
 int arr[8],i;
 for(i=0;i<8;i++) {
  arr[i] = num % k;
  num=num/k;
  if(num == 0)
   break;
 }
  printf("转换为%d进制数为: ",k);
 
 for(;i>=0;i--) {
  switch (arr[i]) {
   case 10:
    printf("A");
    break;
   case 11:
    printf("B");
    break;
   case 12:
    printf("C");
    break;
   case 13:
    printf("D");
    break;
   case 14:
    printf("E");
    break;
   case 15:
    printf("F");
    break;
   default:
    printf("%d",arr[i]);
  }
 }
 printf("\n\n\n");
}

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // insert code here...
    NSLog(@"Hello, World!");
 
 int num,choo; 
 loop:    printf("请选择功能：0.退出  1.十进制转二进制  2.十进制转八进制  3.十进制转十六进制\n"); 
 scanf("%d",&choo); 
 switch (choo) 
 { 
        case 1: 
            printf("请输入要转换的十进制数："); 
            scanf("%d",&num); 
            tran (num,2); 
            goto loop; 
        case 2: 
            printf("请输入要转换的十进制数："); 
            scanf("%d",&num); 
            tran (num,8); 
            goto loop; 
        case 3: 
            printf("请输入要转换的十进制数："); 
            scanf("%d",&num); 
            tran (num,16); 
            goto loop; 
        case 0:break; 
        default : 
            printf("输入有误！请重新输入！\n"); 
            goto loop; 
 }
 
    [pool drain];
    return 0;
}