foo.c: In function ‘main’:
foo.c:4:17: error: lvalue required as left operand of assignment
    4 |  scanf("%b%b",&a=123,&b=500);
      |                 ^
foo.c:4:24: error: lvalue required as left operand of assignment
    4 |  scanf("%b%b",&a=123,&b=500);
      |                        ^