c switch statement -

void display() {     printf("every thing ok"); } void main() {     int ch;     while(1)     {         printf("enter choice");         scanf("%d",&ch);         switch(ch)          {             case 1: clrscr();printf("when choice 1 every thing fine");                     display();                     break;             case 2: clrscr();printf("when chice 2 confusing");                     display();                     break;             case 3: exit(0);             default: printf("enter choice 1 or 2 or exit enter 3");         }     } } 

when trace c program , enter choice 2 calls display function case 1 block. not understand this. please reply explanation. confused.

the compiler re-arranging source statements collapsing basic blocks. debugger matches calls display() in both cases same source line number. usual when optimization enabled.