为什么在 C 中将 1,000,000,000 写为 1000*1000*1000? [英] Why write 1,000,000,000 as 1000*1000*1000 in C?

问题描述

在 Apple 创建的代码中，有这样一行:

In code created by Apple, there is this line:

CMTimeMakeWithSeconds( newDurationSeconds, 1000*1000*1000 )

是否有任何理由将1,000,000,000表示为1000*1000*1000?

Is there any reason to express 1,000,000,000 as 1000*1000*1000?

为什么不用 1000^3 呢?

推荐答案

以乘法方式声明常量的一个原因是为了提高可读性，同时不影响运行时性能.此外，表明作者正在以乘法的方式思考数字.

One reason to declare constants in a multiplicative way is to improve readability, while the run-time performance is not affected. Also, to indicate that the writer was thinking in a multiplicative manner about the number.

考虑一下:

double memoryBytes = 1024 * 1024 * 1024;

显然比:

double memoryBytes = 1073741824;

因为后者乍一看不是 1024 的三次方.

as the latter doesn't look, at first glance, the third power of 1024.

正如 Amin Negm-Awad 提到的，^ 运算符是二进制 XOR.许多语言缺少内置的编译时求幂运算符，因此缺少乘法.

As Amin Negm-Awad mentioned, the ^ operator is the binary XOR. Many languages lack the built-in, compile-time exponentiation operator, hence the multiplication.

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