/in/foo.c: In function 'Search':
/in/foo.c:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.c:17:4: warning: 'flag' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(flag == 0) return -1;
    ^
/in/foo.c: In function 'main':
/in/foo.c:17:4: warning: 'flag' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(flag == 0) return -1;
    ^
/in/foo.c:4:17: note: 'flag' was declared here
  int index = -1,flag,i;
                 ^~~~