我在读c++老师的课堂笔记,他是这样写的:
使用缩进// OK
永远不要依赖运算符优先级-总是使用括号// OK
总是使用{}块-即使是单行//不可以,为什么??
Const对象在比较的左边// OK
对>= 0的变量使用unsigned,这是个不错的技巧
删除后将指针设置为NULL -双重删除保护//不错
第三种方法我不清楚:放一行进去能得到什么
A{…} ?
例如,下面这段奇怪的代码:
int j = 0;
for (int i = 0 ; i < 100 ; ++i)
{
if (i % 2 == 0)
{
j++;
}
}
将其替换为:
int j = 0;
for (int i = 0 ; i < 100 ; ++i)
if (i % 2 == 0)
j++;
使用第一个版本的好处是什么?
除了一些明显的情况外,我在任何地方都使用{}。单行是其中一种情况:
if(condition) return; // OK
if(condition) //
return; // and this is not a one-liner
当你在返回之前添加一些方法时,它可能会伤害你。缩进表示当条件满足时执行return,但它总是返回。
c#中using语句的其他例子
using (D d = new D()) // OK
using (C c = new C(d))
{
c.UseLimitedResource();
}
这相当于
using (D d = new D())
{
using (C c = new C(d))
{
c.UseLimitedResource();
}
}
我正在处理的代码库被那些病态地厌恶大括号的人分散在代码中,对于后来的人来说,它确实可以对可维护性产生影响。
我遇到的最常见的问题是:
if (really incredibly stupidly massively long statement that exceeds the width of the editor) do_foo;
this_looks_like_a_then-statement_but_isn't;
所以当我出现并希望添加一个then语句时,如果我不小心,我很容易以这样的方式结束:
if (really incredibly stupidly massively long statement that exceeds the width of the editor) do_foo;
{
this_looks_like_a_then-statement_but_isn't;
i_want_this_to_be_a_then-statement_but_it's_not;
}
考虑到添加大括号需要1秒左右的时间,并且可以为您节省至少几分钟的调试时间,为什么不选择减少歧义性呢?在我看来这是虚假的节约。
在“总是使用牙套”的营地呆了10年之后,我最近开始不怎么使用牙套了。
主要是受到Bob叔叔关于如何编写干净代码的争论的启发,我现在相信不使用大括号编写代码更具有可读性。
if(guardClause)
throw new SomeException(..)
Bob大叔认为,在if/for语句中编写多行代码是潜在的可读性问题。
e.g.
if(someCondition)
{
doTechnicalThingX();
doTechnicalThingY();
doTechnicalThingZ();
}
应该被重构为
if(someCondition)
doFunctionalThingA();
对我来说,不把大括号放在那里是有帮助的,因为我得到提醒,我在if块中写了太多代码。
正如其他人所提到的,我相信代码风格是团队决策。
我对这位讲师的能力表示怀疑。考虑到他
点:
OK
Would anyone really write (or want to read) (b*b) - ((4*a)*c)?
Some precedences are obvious (or should be), and the extra parentheses
just add to confusion. (On the other hand, you _should_ use the
parentheses in less obvious cases, even if you know that they're not
needed.)
Sort of. There are two wide spread conventions for formatting
conditionals and loops:
if ( cond ) {
code;
}
and:
if ( cond )
{
code;
}
In the first, I'd agree with him. The opening { is not that visible,
so it's best to assume it's always there. In the second, however, I
(and most of the people I've worked with) have no problem with omitting
the braces for a single statement. (Provided, of course, that the
indentation is systematic and that you use this style consistently.
(And a lot of very good programmers, writing very readable code, omit
the braces even when formatting the first way.)
NO. Things like if ( NULL == ptr ) are ugly enough to hinder
readability. Write the comparisons intuitively. (Which in many cases
results in the constant on the right.) His 4 is bad advice; anything
which makes the code unnatural makes it less readable.
NO. Anything but int is reserved for special cases. To
experienced C and C++ programmers, the use of unsigned signals bit
operators. C++ doesn't have a real cardinal type (or any other
effective subrange type); unsigned doesn't work for numeric values,
because of the promotion rules. Numerical values on which no
arithmetic operations would make sense, like serial numbers, could
presumably be unsigned. I'd argue against it, however, because it
sends the wrong message: bitwise operations don't make sense either.
The basic rule is that integral types are int, _unless_ there is a
significant reason for using another type.
NO. Doing this systematically is misleading, and doesn't actually
protect against anything. In strict OO code, delete this; is often
the most frequent case (and you can't set this to NULL), and
otherwise, most delete are in destructors, so you can't access the
pointer later anyway. And setting it to NULL doesn't do anything
about any other pointers floating around. Setting the pointer
systematically to NULL gives a false sense of security, and doesn't
really buy you anything.
查看任何典型参考文献中的代码。Stroustrup违反
除了第一条,你给出的每一条规则。
我建议你换个讲师。一个真正知道什么的人
他说的是。