尝试计算BASH中的圆的半径和面积 [英] Trying to calculate radius and area of circle in BASH

问题描述

我正在尝试编写一个基本脚本来计算圆的半径和面积，其中PI = 3.14，并给出了周长.我对脚本编写非常陌生，但似乎无法弄清楚.

I'm trying to write a basic script to calculate the radius and area of a circle, where PI=3.14, and the circumference is given. I am very very new to scripting, and I can't seem to figure this out.

#!/bin/bash
PI=3.14
CIRC=5
RAD=echo "((CIRC/2*PI))" | bc-l
printf "Radius: %.2f" $RAD
AREA=echo "((PI*RAD**2))" | bc-l
printf "Area: %.2f" $AREA

两个方程的总和没有存储在这些变量中，我也不知道为什么.我希望有人可以帮助解释.

The sum of both equations are not being stored in those variables, and I have no idea why. I hope someone can help explain.

推荐答案

下面的脚本可以做到:

#!/bin/bash
pi=3.14
circ=5
rad=$( echo "scale=2;$circ / (2 * $pi)" | bc )
printf "Radius: %.2f\n" $rad
area=$( echo "scale=2;$pi * $rad * $rad" | bc )
printf "Area: %.2f\n" $area

注释

1. 请参见 [命令替换] .
2. 请不要在脚本中使用完整的大写变量，因为它们通常是系统保留的，请检查 [此] .
3. scale 和 bc 控制精度，请检查[此] .

1. See [ command substitution ].
2. Never use full uppercase variables in your script as they are usually reserved for the system, check [ this ].
3. scale with bc controls the precision, check [ this ].

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