在D中打印浮点数

It's been quite a while since I last used D Programming Language, and now I'm using it for some project that involves scientific calculations.

自从我上次使用D编程语言以来已经有一段时间了,现在我将它用于一些涉及科学计算的项目。

I have a bunch of floating point data, but when I print them using writefln, I get results like: 4.62593E-172 which is a zero! How do I use string formatting % stuff to print such things as 0?

我有一堆浮点数据,但是当我使用writefln打印它们时,我得到的结果如下:4.62593E-172这是一个零!如何使用字符串格式化%stuff来打印0这样的东西?

Right now I'm using a hack:

现在我正在使用黑客:

    if( abs(a) < 0.0000001 )
        writefln(0);
    else
        writefln(a);

it does the job, but I want to do it using the formatting operations, if possible.

它完成了这项工作,但我希望使用格式化操作,如果可能的话。

UPDATE

someone suggested writefln("%.3f", a) but the problem with it is that it prints needless extra zeros, i.e. 0 becomes 0.000 and 1.2 becomes 1.200
Can I make it also remove the trailing zeros?

有人建议使用writefln(“%。3f”,a),但问题是它打印了不必要的额外零,即0变为0.000而1.2变为1.200我可以使它也删除尾随零吗?

4 个解决方案

#1

Short answer: This can't be done with printf format specifiers.

简短回答:使用printf格式说明符无法做到这一点。

Since D uses the same formatting as C99's vsprintf(), you find your answer in this thread: Avoid trailing zeroes in printf()

由于D使用与C99的vsprintf()相同的格式,因此您可以在此主题中找到答案:避免在printf()中使用尾随零

#2

Try something like

尝试类似的东西

writefln("%.3f", a);

#3

Federico's answer should work, for more information check the format specifiers section.

Federico的答案应该有效,有关更多信息,请查看格式说明符部分。

#4

-1

I see you are currently using Phobos, however what you are trying to do is supported in Tango.

我发现你现在正在使用Phobos,但是Tango支持你想要做的事情。

Stdout.formatln("{:f2}", 1.2);

will print "1.20"

将打印“1.20”

#1