/in/foo.c: In function 'main':
/in/foo.c:11:17: error: 'X' undeclared (first use in this function)
  else if(x>=10&&X<25)
                 ^
/in/foo.c:11:17: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:13:2: error: expected ';' before 'else'
  else
  ^~~~