ES.44: Don't depend on order of evaluation of function arguments
ES.44: 不要让执行结果受函数参数的求值次序影响
Reason（原因）
Because that order is unspecified.
因为函数参数的求值次序是无定义的。
Note（注意）
C 17 tightens up the rules for the order of evaluation, but the order of evaluation of function arguments is still unspecified.
C 17收紧了运算次序规则，但是函数参数的求值次序依然是无定义的。
Example（示例）
代码语言：javascript复制int i = 0;
f( i, i);The call will most likely be f(0, 1) or f(1, 0), but you don't know which. Technically, the behavior is undefined. In C 17, this code does not have undefined behavior, but it is still not specified which argument is evaluated first.
调用的结果很可能是f(0，1)或者f(1，0)，但是不知道会是哪一个。技术上，这个行为是无定义的。在C 17中，这段代码不会是一个无定义的行为，但是依然没有明确那个参数先求值。
Example（示例）
Overloaded operators can lead to order of evaluation problems:
重载的运算符可能引入计算次序的问题。
代码语言：javascript复制f1()->m(f2()); // m(f1(), f2())
cout << f1() << f2(); // operator<<(operator<<(cout, f1()), f2())In C 17, these examples work as expected (left to right) and assignments are evaluated right to left (just as ='s binding is right-to-left)
在C 17中，这些代码示例可以像期待的那样执行（从左向右），同时赋值会从右向左计算（就像赋值运算符=绑定了从右向左计算次序）
代码语言：javascript复制f1() = f2(); // undefined behavior in C 14; in C 17, f2() is evaluated before f1()Enforcement（实施建议）
Can be detected by a good analyzer.
这个问题可以被实现良好的代码解析器检出。
链接
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es44-dont-depend-on-order-of-evaluation-of-function-arguments
