August 2021
Intermediate to advanced
450 pages
9h 36m
Chinese
Content preview from C++程序设计：原理与实践（基础篇）（原书第2版）
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8.6.1 表达式计算
表达式中子表达式计算顺序所遵循的规则，是按优化编译器的需求设计的，而不是为了方便程序员。这很不幸，但不管怎样你应该避免复杂的表达式，有一条简单的原则可以帮你远离麻烦：如果你在表达式中改变一个变量的值，不要在同一个表达式中再读或写这个变量。例如：
不幸的是，如果你写出这样有问题的代码，并不是所有编译器都能给出警告。这段代码的问题在于，如果你将代码迁移到另外一台计算机，使用另一个编译器，或者改变编译器优化设置，运行结果不保证一致。不同的编译器确实会对这段代码得到不同结果，所以不要这么编写程序。
特别要注意的是，=（赋值符）在表达式中只是又一种运算符而已，并没有特殊的地位，因此不能保证赋值符左边的子表达式在右边的子表达式之前计算。这就是为什么v[++i]=i；结果是不确定的。
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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