foo.cc: In function 'int in()':
foo.cc:9:7: warning: unused variable 'c' [-Wunused-variable]
  char c;
       ^
foo.cc:10:6: warning: unused variable 'i' [-Wunused-variable]
  int i = 0;
      ^
foo.cc:22:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
foo.cc: In function 'int main()':
foo.cc:44:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i < strlen(str);i++)
                   ~~^~~~~~~~~~~~~
foo.cc:42:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d\n",&p1,&p2,&p3);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc: In function 'int in()':
foo.cc:21:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",str);
  ~~~~~^~~~~~~~~~