foo.cc: In function 'int findmax(int*)':
foo.cc:8:16: error: 'n' was not declared in this scope
  for(int i=0;i<n;i++)
                ^
foo.cc:10:1: error: expected primary-expression before '}' token
 }
 ^
foo.cc:10:1: warning: no return statement in function returning non-void [-Wreturn-type]
foo.cc: In function 'int main()':
foo.cc:34:8: error: 'strlen' was not declared in this scope
  int n=strlen(prime);
        ^~~~~~
foo.cc:34:8: note: suggested alternative: 'mbrlen'
  int n=strlen(prime);
        ^~~~~~
        mbrlen

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