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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3.9.1 安全转换
在3.4节中，我们发现不能直接对char进行相加，或者将一个double与一个int比较。但是，C++提供了间接方式来完成这些操作。在有必要时，一个char可以转换成一个int，而一个int也可以转换成一个double。例如：
这里的i1和i2都被赋值为120，它是字符'x'在最流行的8比特字符集ASCII中的整型值。这是一个简单和安全的方法，通过它可以获得一个字符的数字表示。我们称这种char-int的转换为安全的，这是由于没有信息丢失；也就是说，我们可以将int结果拷贝回一个char中，并且得到原始的值：
输出结果为
一个值被转换成一个等价的值，或是一个最接近等价的值（对于double），在这种意义下，下面这些转换就是安全的：
最有用处的转换是从int到double，这是由于它允许在表达式中混合使用int和double： ...
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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.