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。

如果你是一个编译器，这没有任何区别。两者是一样的。

但是对于程序员来说，第一个更清晰，更容易阅读，更不容易出错。

有许多可能的方法来编写控制语句;它们的某些组合可能共存而不损害易读性，但其他组合将引起麻烦。的风格

if (condition)
  statement;

可以与其他一些编写控制语句的方法很好地共存，但与其他方法就不那么好了。如果多行受控语句被写成:

if (condition)
{
  statement;
  statement;
}

那么，从视觉上看，哪些if语句控制单行，哪些语句控制多行就很明显了。然而，多行If语句被写成:

if (condition) {
  statement;
  statement;
}

那么，如果构造不添加必要的大括号，那么试图扩展单个语句的可能性就会高得多。

如果代码库大量使用这种形式，那么下一行的单个语句if语句也可能有问题

if (condition) statement;

我个人的偏好是将语句放在自己的行上通常可以提高易读性，除非有许多if语句具有类似的控制块，例如。

if (x1 > xmax) x1 = xmax;
if (x1 < xmin) x1 = xmin;
if (x2 > xmax) x2 = xmax;
if (x2 < xmin) x2 = xmin;
etc.

在这种情况下，我通常会在这些if语句的前面和后面加上一个空行，以便在视觉上将它们与其他代码分开。在相同的缩进处使用一系列以if开头的语句将提供一个清晰的视觉指示，表明有不寻常的地方。

它通过清楚地定义循环和条件块的范围，使您的代码更具可读性。它还可以避免你意外出错。

我能想到的最贴切的例子是:

if(someCondition)
   if(someOtherCondition)
      DoSomething();
else
   DoSomethingElse();

Which if will the else be paired with? Indentation implies that the outer if gets the else, but that's not actually how the compiler will see it; the inner if will get the else, and the outer if doesn't. You would have to know that (or see it behave that way in debugging mode) to figure out by inspection why this code might be failing your expectations. It gets more confusing if you know Python; in that case you know that indentation defines code blocks, so you would expect it to evaluate according to the indentation. C#, however, doesn't give a flying flip about whitespace.

话虽如此，从表面上看，我并不特别同意这个“总是使用括号”的规则。它使代码的垂直噪声非常大，降低了快速读取代码的能力。如果语句是:

if(someCondition)
   DoSomething();

... then it should be written just like this. The statement "always use brackets" sounds like "always surround mathematical operations with parentheses". That would turn the very simple statement a * b + c / d into ((a * b) + (c / d)), introducing the possibility of missing a close-paren (the bane of many a coder), and for what? The order of operations is well-known and well-enforced, so the parentheses are redundant. You'd only use parentheses to enforce a different order of operations than would normally be applied: a * (b+c) / d for instance. Block braces are similar; use them to define what you want to do in cases where it differs from the default, and is not "obvious" (subjective, but usually pretty common-sense).

它更直观，更容易理解。它使意图明确。

它还确保当新用户在添加新代码语句时不知不觉地漏掉{，}时，代码不会中断。