/in/foo.c: In function 'Length':
/in/foo.c:15:4: error: 'n' undeclared (first use in this function)
    n++;
    ^
/in/foo.c:15:4: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:17:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^