为什么在浮点数末尾使用字母f？ [英] Why is the letter f used at the end of a float no.?

问题描述

我只想了解一些相关信息。

I just wanted some information about this.

float n = 2.99944323200023f

文字末尾的 f 是什么？这叫什么？为什么使用？

What does the f at the end of the literal do? What is it called? Why is it used?

推荐答案

f 表示它是浮点数文字，而不是双字面（它本来就是隐含的。）它没有我所知道的特定技术名称 - 如果我需要专门提及它，我倾向于将其称为字母后缀，尽管这是有点武断！

The f indicates it's a floating point literal, not a double literal (which it would implicitly be otherwise.) It hasn't got a particular technical name that I know of - I tend to call it the "letter suffix" if I need to refer to it specifically, though that's somewhat arbitrary!

例如：

float f = 3.14f; //Compiles
float f = 3.14;   //Doesn't compile, because you're trying to put a double literal in a float without a cast.

您当然可以这样做：

float f = (float)3.14;

...它完成了近乎相同的事情，但F是一个更整洁，更简洁的方式显示它。

...which accomplishes near enough the same thing, but the F is a neater, more concise way of showing it.

为什么选择双重作为默认而不是浮动？好吧，现在99％的情况下浮点数的双倍内存要求不是问题，并且它们提供的额外准确性在很多情况下都是有益的 - 所以你可以说这是合理的默认值。

Why was double chosen as the default rather than float? Well, these days the memory requirements of a double over a float aren't an issue in 99% of cases, and the extra accuracy they provide is beneficial in a lot of cases - so you could argue that's the sensible default.

请注意，您可以通过在结尾处放置 d 来明确地将十进制文字显示为double：

Note that you can explicitly show a decimal literal as a double by putting a d at the end also:

double d = 3.14d;

...但是因为它无论如何都是双倍值，所以没有效果。有些人可能会主张它提倡它更清楚你的意思是什么字面类型，但我个人觉得它只是杂乱的代码（除非你有很多浮动文字，你要强调这个文字确实意味着一个双重，遗漏f不仅仅是一个错误。）

...but because it's a double value anyway, this has no effect. Some people might argue for it advocating it's clearer what literal type you mean, but personally I think it just clutters code (unless perhaps you have a lot of float literals hanging around and you want to emphasise that this literal is indeed meant to be a double, and the omission of the f isn't just a bug.)

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