foo.cc: In function 'bool cmp()':
foo.cc:11:6: warning: unused variable 'f' [-Wunused-variable]
  int f=1;
      ^
foo.cc: At global scope:
foo.cc:62:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main() {
      ^
foo.cc: In function 'bool cmp()':
foo.cc:24:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

自豪的采用jd5进行评测(github.com/masnn/jd5)