/in/foo.c: In function 'main':
/in/foo.c:6:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'a'
   a=10,b=20;
   ^
/in/foo.c:7:2: error: 'sum' undeclared (first use in this function)
  sum=a+b
  ^~~
/in/foo.c:7:2: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:7:8: error: 'b' undeclared (first use in this function)
  sum=a+b
        ^
/in/foo.c:8:3: error: expected ';' before 'printf'
   printf("%d",sum);
   ^~~~~~