foo.cc:7:0: warning: "shi" redefined
 #define shi printf("%d",s);
 
foo.cc:3:0: note: this is the location of the previous definition
 #define shi {
 
foo.cc:7:13: error: expected initializer before 'printf'
 #define shi printf("%d",s);
             ^
foo.cc:11:1: note: in expansion of macro 'shi'
 shi
 ^~~
foo.cc:5:18: error: expected constructor, destructor, or type conversion before '(' token
 #define ruo scanf("%d%d",&a,&b);
                  ^
foo.cc:13:1: note: in expansion of macro 'ruo'
 ruo
 ^~~
foo.cc:6:12: error: 's' does not name a type
 #define ni s=a+b;
            ^
foo.cc:14:1: note: in expansion of macro 'ni'
 ni
 ^~
foo.cc:7:19: error: expected constructor, destructor, or type conversion before '(' token
 #define shi printf("%d",s);
                   ^
foo.cc:15:1: note: in expansion of macro 'shi'
 shi
 ^~~
foo.cc:8:14: error: expected unqualified-id before 'return'
 #define shen return 0;
              ^
foo.cc:16:1: note: in expansion of macro 'shen'
 shen
 ^~~~
foo.cc:9:13: error: expected declaration before '}' token
 #define niu }
             ^
foo.cc:17:1: note: in expansion of macro 'niu'
 niu
 ^~~

自豪的采用 HydroJudge 进行评测(github.com/hydro-dev/HydroJudge)