/in/foo.c: In function 'isprime':
/in/foo.c:12:4: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(k==n) return 1;
    ^
/in/foo.c: In function 'main':
/in/foo.c:12:4: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(k==n) return 1;
    ^
/in/foo.c:4:6: note: 'k' was declared here
  int k;
      ^