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如何在linux脚本中创建计算器？

tag-icon • tag-icon shell-script string
如何在linux脚本中创建计算器？

我正在尝试创建一个计算器：

echo "What is your number?"
read n1 

echo "what is your second number?"
read n2

echo "what do you want to do?"
echo "1. add"
echo "2. subtract"
echo "3. divide"
echo "4. multiply"
read ans


if 
ans=$(( $n1+$n2 )); then
echo $ans

elif
ans=$(( $n1-$n2 )); then
echo $ans

elif
ans=$(( $n1/$n2 )); then
echo $ans

elif
ans=$(( $n1*$n2 )); then
echo $ans

else

但是当我插入字母时它显示0。我该如何改进它？有时它也会给我错误的答案。

答案1

尝试使用while loop：

input="yes"
while [[ $input = "yes" ]]
do

    PS3="Press 1 for Addition, 2 for subtraction, 3 for multiplication and 4 for division: "
    select math in Addition Subtraction Multiplication Division
    do
        case "$math" in
        Addition)
            echo "Enter first no:"
            read num1
            echo "Enter second no:"
            read num2
            result=`expr $num1 + $num2`
            echo Answer: $result
            break
        ;;
        Subtraction)
            echo "Enter first no:"
            read num1
            echo "Enter second no:"
            read num2
            result=`expr $num1 - $num2`
            echo Answer: $result
            break
        ;;
        Multiplication)
            echo "Enter first no:"
            read num1
            echo "Enter second no:"
            read num2
            result=`expr $num1 * $num2`
            echo Answer: $result
            break
        ;;
        Division)
            echo "Enter first no:"
            read num1
            echo "Enter second no:"
            read num2
            result=$(expr "scale=2; $num1/$num2" | bc)
            echo Answer = $result
            break
        ;;
        *)
            echo Choose 1 to 4 only!!!!
            break
        ;;
    esac
    done

done

答案2

clear
sum=0
i="y"

echo " Enter one no." 
read n1 
echo "Enter second no."
read n2

while[ $i = "y" ]
do 
echo "1.Addition" 
echo "2.Subtraction" 
echo "3.Multiplication" 
echo "4.Division" 

echo "Enter your choice" 
read ch 

case $ch in 
1)sum=`expr $n1 + $n2` 
   echo "Sum ="$sum;; 

2)sum=`expr $n1 - $n2` 
   echo "Sub = "$sum;; 

3)sum=`expr $n1 \* $n2` 
   echo "Mul = "$sum;; 

4)sum=`expr $n1 / $n2` 
    echo "Div = "$sum;; 

*)echo "Invalid choice";; 
esac 

echo "Do u want to continue ?" 
read i 
if [ $i != "y" ] then
      exit 
fi 
done

答案3

试试这个更简单的。

#!/bin/bash

echo "enter first number"
read p
echo "enter second number"
read q
echo  "enter the  operator"
read r
sum=`expr $p "$r" $q`
echo  "the total" $sum

答案4

echo "Enter Your Choise : "
echo "1.Addition"
echo "2.Substtaction"
echo "3.Multiplication"
echo "4.Division"
read opr
echo "Enter first Number : "
read n1
echo "Enter second Number : "
read n2
if [$opr=1] then
  echo `expr ans=$((n1+n2))`
elif [$opr=2] then
  echo `expr ans=$((n1-n2))`
elif [$opr=3] then
  echo `expr ans=$((n1*n2))`
else [$opr=4] then
  echo `expr ans=$((n1/n2))`

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