Unix - 使用 shell 脚本的简单计算器 [已编辑]

Question

我刚开始在 Unix 操作系统中使用 shell 编写一个简单的脚本，我尝试先编写一个简单的计算器代码，该代码让用户选择一个操作（加法、减法等），它将被保存为一个变量（选择）然后，让用户插入任意两个数字，这些数字将被保存为变量（num1 和 num2） 最后，执行操作，检查代码以获取更多信息

echo "+--------------------+"
echo "| Simple Calculator  |"
echo "+--------------------+"
echo "This shell is a simple calculator that takes two numbers from user, perform math operation then return the results"
echo Please choose an operation from the following:
echo 1,Addition
echo 2,Subtraction
echo 3,Multiplication
echo 4,division
echo Please choose an operation
read choice
echo Please insert the 1st number:
read num1
echo Please insert the 2ed number:
read num2
case $choice
1) echo "The result of addition operation is:`expr $num1 + $num2`;;
2) echo The result of Subtraction operation is:`expr $num1 - $num2`;;
3) echo The result of Multiplication operation is:`expr $num1 \* $num2`;;
4) echo The result of Division operation is:`expr $num1 \/ $num2`;;
*) echo invalid operation, please try again;;
esac

不幸的是，即使我做了一些更改，代码仍然无法正常工作，它一直显示此错误：

./shell.sh: line 16: syntax error near unexpected token 1'./shell.sh: line 16: 1) echo 加法运算结果为： expr $num1 + $num2 ;;'

注意：此代码不适用于大学项目，也不适用于我探索和学习的家庭作业。

Answer 1

您的case语法错误。

http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_03.html

解释如何用case ； 因为你想做的事情并没有从你的源代码中变得清晰，所以我真的不能给你太多关于如何做的信息:(

Answer 2

为了娱乐：

#!/bin/bash
echo "Better calculator"
while read -r -p 'Enter expression (CTRL-C or CTRL-D for end)> ' exp
do
    echo "$exp =" $(bc -l <<< "$exp")
done

或者直接输入命令提示符：

bc -l

但可能你的老师想要不同的东西...... :)

Answer 3

所以我现在知道我的错误了：D

我的错误在第 15 行，我应该在选择后输入“in”

"case $choose in" --> 这在你使用 "case" 时非常重要

简单吧！ --> 这让我疯狂了一阵子"^__^

Answer 4

echo "+--------------------+"
echo "| Simple Calculator  |"
echo "+--------------------+"
echo "This shell is a simple calculator that takes two numbers from user, perform math operation then return the results"
echo Please choose an operation from the following:
echo 1,Addition
echo 2,Subtraction
echo 3,Multiplication
echo 4,division
echo Please choose an operation
read choice
echo Please insert the 1st number:
read num1
echo Please insert the 2ed number:
read num2
case $choice
1) echo "The result of addition operation is:`expr $num1 + $num2`;;
2) echo The result of Subtraction operation is:`expr $num1 - $num2`;;
3) echo The result of Multiplication operation is:`expr $num1 \* $num2`;;
4) echo The result of Division operation is:`expr $num1 \/ $num2`;;
*) echo invalid operation, please try again;;
esac