Understanding Qsort in C Language

I have a question about C language.

In the qsort assignment, I submitted the following code:

printf("a order:");
scanf("%c", & ad);
qsort(sin,9,sizeof(int), ad=='a'?cmp_u:cmp_d);

'a'?cmp_u:cmp_d); I was told to write separately using the if statement, but I got an error...
Could someone tell me how to write it?

 if(ad=='a')
        qsort(sin,9,cmp_u);
    else
        qsort(sin,9,cmp_d);