int a = 7; 3 = a;
在标准的C上下文无关语法中,我发现这个语句在语法上是有效的.
然后是语义错误,如5.17中所述：
All require a modifiable lvalue as their left operand and return an lvalue referring to the left operand.
左值是一个语义概念,而不是语法概念.
