/in/foo.c: In function 'main':
/in/foo.c:5:8: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'b'
  int a b;
        ^
/in/foo.c:5:8: error: 'b' undeclared (first use in this function)
/in/foo.c:5:8: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:6:2: error: 'a' undeclared (first use in this function)
  a=10,b=20;
  ^
/in/foo.c:6:6: warning: left-hand operand of comma expression has no effect [-Wunused-value]
  a=10,b=20;
      ^
/in/foo.c:7:2: error: 'c' undeclared (first use in this function)
  c=a+b;
  ^
/in/foo.c:9:1: error: expected ';' before '}' token
 }
 ^