在bash中，如何将两个变量相除并输出四舍五入至小数点后5位的答案? [英] In bash how do I divide two variables and output the answer rounded upto 5 decimal digits?

问题描述

我将两个变量作为输入，除以两个变量后，我想将输出舍入为5位小数位数.我已经尝试过这种方式->

I took two variables as input and after dividing them, I want to get the output rounded up to 5 decimal digits. I have tried this way ->

sum=12
n=7
output=$("scale=5;sum/n"|bc)
echo $output

我的代码未显示任何输出.我该怎么办?

My code isn't showing any output. What can I do??

TestCase:

如果 sum = 3345699 和 n = 1000000 然后(sum/n)= 3.345699 ，则应将其更改为 3.34570.

If sum=3345699 and n=1000000 then (sum/n)=3.345699, it should be changed into 3.34570.

推荐答案

此处的问题是您错过了提供的 echo (或 printf 或其他任何东西)数据到 bc :

The problem here is that you missed the echo (or printf or any other thing) to provide the data to bc:

$ echo "scale=5; 12/7" | bc
1.71428

此外，正如cnicutar在评论中指出的那样，您需要使用 $ 来引用变量. sum 是一个字符串， $ sum 是变量 sum 的值.
总之，您的代码段应该像这样:

Also, as noted by cnicutar in comments, you need to use $ to refer to the variables. sum is a string, $sum is the value of the variable sum.
All together, your snippet should be like:

sum=12
n=7
output=$(echo "scale=5;$sum/$n" | bc)
echo "$output"

这将返回 1.71428 .

否则，使用"scale = 5; sum/n" | bc ，您只是在分配分配，并使 bc 失败:

Otherwise, with "scale=5;sum/n"|bc you are just piping an assignment and makes bc fail:

$ "scale=5;sum/n"|bc
bash: scale=5;sum/n: No such file or directory

---

然后，您说要对结果进行四舍五入，但这种情况目前还没有发生:

---

You then say that you want to have the result rounded, which does not happen right now:

$ sum=3345699
$ n=1000000
$ echo "scale=5;($sum/$n)" | bc
3.34569

这需要一种不同的方法，因为 bc 不会四舍五入.您可以将 printf 与％.Xf 一起使用以四舍五入为 X 十进制数字，这可以做到:

This needs a different approach, since bc does not round. You can use printf together with %.Xf to round to X decimal numbers, which does:

$ printf "%.5f" "$(echo "scale=10;$sum/$n" | bc)"
3.34570

看到我给它一个很大的比例，这样 printf 的小数点数就足以正确舍入.

See I give it a big scale, so that then printf has decimals numbers enough to round properly.

这篇关于在bash中，如何将两个变量相除并输出四舍五入至小数点后5位的答案?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！