/in/foo.c: In function 'main':
/in/foo.c:6:13: error: 'a' undeclared (first use in this function)
    6 |     short x=a+b;
      |             ^
/in/foo.c:6:13: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:6:15: error: 'b' undeclared (first use in this function)
    6 |     short x=a+b;
      |               ^
/in/foo.c:7:9: error: 'cout' undeclared (first use in this function)
    7 |         cout<< "x" <<endl;
      |         ^~~~
/in/foo.c:7:22: error: 'endl' undeclared (first use in this function)
    7 |         cout<< "x" <<endl;
      |                      ^~~~
/in/foo.c:6:11: warning: unused variable 'x' [-Wunused-variable]
    6 |     short x=a+b;
      |           ^