Question

刚学shell脚本写了个小 计算器，加减除都可以，乘法不行，哪儿错了

#!/bin/bash
echo "first number"
read a
echo "fangfa"
read fangfa
echo "second number"
read b
if [ $fangfa = "+" ];then
echo $(($a+$b))
elif [ $fangfa = "-" ];then
echo $(($a-$b))
elif [ $fangfa = " \* " ];then
echo $(($a*$b))
else
echo $(($a/$b))
fi

Answer 1

你的问题在：elif [ $fangfa = " \* " ]; 这句并不能判断到“*“乘号；
正确的结果如下：
#!/bin/bash
echo "first number"
read a
echo "fangfa"
read fangfa
echo "second number"
read b
if [ "$fangfa" = "+" ];then
echo $(($a+$b))
elif [ "$fangfa" = "-" ];then
echo $(($a-$b))
elif [ "$fangfa" = "*" ];then
echo $(($a*$b))
elif [ "$fangfa" = "/" ];then
echo $(($a/$b))
fi
===============================================
脚本优化版本：
#!/bin/bash

read -p "input first number: " num1
read -p "input operator: " operator
read -p "input second number: " num2

if [ "$operator" == "+" ];then
echo " num1 + num2 = $(($num1+$num2))"
elif [ "$operator" == "-" ];then
echo "num1 - num2 = $(($num1-$num2))"
elif [ "$operator" == "*" ];then
echo "num1 * num2 = $(($num1*$num2))"
elif [ "$operator" == "/" ];then
echo "num1 / num2 = $(($num1/$num2))"
fi

Answer 2

elif [ "$fangfa" = "*" ];then
这样就可以了

Answer 3

你给算法里也加上反斜杠试试。

追问

不行，应该不是算法原因，报错是条件有冲突

追答

因为输入可能还是其他种情况，所以建议将四个条件都写上，最后写上else 是除了四种法则其他情况，输出错误。