The shortest 6.5 exercise variant!

[Jemcik]

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) 
{
    @autoreleasepool 
    {
        long long int num;
        printf("Enter an integer number (max 17 digits): ");
        scanf("%lli", &num);
        BOOL sign = num < 0 ? TRUE : FALSE;
        
        for (sign ? num = -num : num; num; num /= 10)
            printf("%lli", num%10);
        sign ? printf("-\n") : printf("\n");
    }
    return 0;
}

P.S. Some explanation needed?

[alexsom]

It looks good. Yes, I would like some explanations if you don't mind. thanks