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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8.2.3 默认初始化
你可能已经注意到了，我们通常不对string、vector等对象进行初始化。例如：
这并不是“变量必须先初始化再使用”这条规则的例外情况。之所以出现这种情况，是因为我们定义string类型和vector类型时定义了默认初始化机制，如果代码中不显式进行初始化，这两种对象就会被用一个默认值进行初始化。因此，上述代码执行到循环时，v的值为空（不包含任何元素），s的值为空串（""）。保证默认初始化的机制称为默认构造函数，参见9.7.3节。
不幸的是，C++不允许我们对内置类型设置默认初始化功能。全局变量会被默认初始化为0，但你应该尽量少用全局变量。而最常使用的变量——局部变量和类成员——是不会被初始化的，除非你对其进行初始化（或提供一个默认构造函数）。我们已经提示过你了，你在实践中一定要注意！
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.