“无效算术运算符"在 bash 中进行浮点运算时

问题描述

这是我的脚本:

d1=0.003
d2=0.0008
d1d2=$((d1 + d2))

mean1=7
mean2=5
meandiff=$((mean1 - mean2))

echo $meandiff
echo $d1d2

但没有得到我想要的输出:

But instead of getting my intended output of:

0.0038
2

我收到错误Invalid Arithmetic Operator，(错误标记是.003")?

推荐答案

bash 不支持浮点运算.您需要使用像 bc 这样的外部实用程序.

bash does not support floating-point arithmetic. You need to use an external utility like bc.

# Like everything else in shell, these are strings, not
# floating-point values
d1=0.003
d2=0.0008

# bc parses its input to perform math
d1d2=$(echo "$d1 + $d2" | bc)

# These, too, are strings (not integers)
mean1=7
mean2=5

# $((...)) is a built-in construct that can parse
# its contents as integers; valid identifiers
# are recursively resolved as variables.
meandiff=$((mean1 - mean2))

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