如何让sprintf忽略尾随零 [英] How to have sprintf to ignore trailing zeros

问题描述

我想将数字转换为小数点右边最多 15个数字的字符串.最多 的意思是，如果最后一位全为零，则打印这些位是无用的.

I want to convert a number to a string with at most 15 digits to the right of the decimal point. By at most i mean that if last digits are all zeros it is useless to print them.

例如:

sprintf('%.15f', 3.0001)

==> '3.000100000000000'

到目前为止，一切都很好，但是由于所有的尾随数字都为零，我更希望:

So far so good, but here as all trailing digits are all zeros, I would have prefered:

==> '3.0001' 

是否有使用sprintf格式说明符的简单方法，还是应该手动对输出进行后处理以删除尾随的零?

Is there a simple way to do it with sprintf format specifiers or should I manually post-process output to remove trailing zeros ?

注意:我正在与matlab合作，以防sprintf有其他替代方法.

NB: I'm working with matlab in case there would be any other aternative to sprintf.

推荐答案

只需使用g而不是f:

sprintf('%.15g', 3.0001)

ans =

3.0001

来自doc sprintf

• ％g％e或％f的更紧凑形式，没有结尾的零

对于小于0.0001(1e-4)的数字，上述方法将失败，在这种情况下，另一种解决方案是使用％f，然后regexprep在这里，它用一个空格替换一个更多的零:

The above method fails for numbers lower than 0.0001 (1e-4), in which case an alternative solution is to use %f and then regexprep here it replaces one more more zeros followed by a space with a space:

str = sprintf('%.15f ',mat);
str = regexprep(str,'[0]+ ',' ')

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此方法还存在一个问题，即删除了这些有效数字后，数字小于5e-16(小数点右边的15位数字只有零).

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This method also has an issue with numbers lower than 5e-16 (such that there are only zeros for 15 digits to the right of the decimal point) having these significant digits removed.

要解决此问题，而不是盲目地替换零，我们可以替换范围为1-9的数字，后跟一个或多个零，然后替换为该数字后跟空格的空格:

To solve this instead of blindly replacing zeros, we can replace a digit in the range 1-9 followed by one or more zeros and then a space with that digit followed by a space:

str = sprintf('%.15f ',mat);
str=regexprep(str,'([1-9])[0]+ ','$1 ')

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