Shell 脚本 - 添加内存功能 [英] Shell Script - Adding memory functionality

问题描述

#!/bin/bash

while true
do
     if [[ $# -eq 0 ]] ; then
         echo Enter operand1 value:
         read operand1
 
         # Offer choices
         echo 1. Addition
         echo 2. Subtraction
         echo 3. Multiplication
         echo 4. Division
         echo 5. Exit
 
         echo Enter your choice:
         read choice

         if [[ $choice != 1 || 2 || 3 || 4 || 5 ]] ; then
             echo Sorry $choice is not a valid operator - please try again 
             echo Enter your choice:
             read choice
         else 
             Continue 
         fi
 
         echo Enter operand2 value:
         read operand2
 
         # get operands and start computing based on the user's choice
         if [[ $choice -eq 1 ]] ; then
             echo ----------------------------------------
             echo Addition of $operand1 and $operand2 is $((operand1+operand2))
             echo ----------------------------------------
             echo
         elif [[ $choice -eq 2 ]] ; then
             echo ----------------------------------------
             echo Subtraction of $operand1 and $operand2 is $((operand1-operand2))
             echo ----------------------------------------
             echo
         elif [[ $choice -eq 3 ]] ; then
             echo ----------------------------------------
             echo Multiplication of $operand1 and $operand2 is $((operand1*operand2))
             echo ----------------------------------------
             echo
         elif [[ $choice -eq 4 && operand2 -eq 0 ]] ; then
             echo Can not divide by 0 please try again 
             echo Please enter operand2
             read operand2
             echo ----------------------------------------
             echo Division of $operand1 and $operand2 is $((operand1/operand2))
             echo ----------------------------------------
             echo    
          elif [[ $choice -eq 4 && operand2 -ne 0 ]] ; then
             echo ----------------------------------------
             echo Division of $operand1 and $operand2 is $((operand1/operand2))
             echo ----------------------------------------
             echo    
         elif [[ $choice -eq 5 ]] ; then
             exit    
         else
             echo ----------------------------------------
             echo Invalid choice.. Please try again
             echo ----------------------------------------
             echo
         fi        
   else
             echo ----------------------------------------
             echo You either passed too many parameters or too less
             echo than the optimum requirement.
             echo
             echo This program accepts a maximum of 2 arguments or no
             echo argument at all in order to run successfully.
             echo ----------------------------------------
   fi
done

我希望为上面的代码添加功能，以便每个后续操作都将使用先前的结果，提示用户输入下一个运算符和操作数，以便用户不必再次输入第一个操作数，只需将其存储在内存中.我似乎想不出任何方法来做到这一点 - 有什么建议吗?

I am looking to add functionality to the above code so that each subsequent operation will use the previous result, prompt the user for the next operator and operand so that the user doesn't have to enter the first operand again and it simply stores it in memory. I cant seem to think of any ways to do this - any advice?

推荐答案

您应该将结果存储在这样的变量中:

You should store the result in a variable like this:

result=$((operand1+operand2))

然后你的第一个 if 语句可以检查这个变量是否有值，如果有，跳过 read 并使用它.

Then your first if statement can check if this variable has a value, and if it does, skip the read and use it instead.

if [[ $result == "" ]]; then
    echo Enter operand1 value:
    read operand1
else
    operand1=$result
    echo "Operand 1 is: $result"
    echo ""
fi
...

这是您的代码的工作版本:

Here is the working version of your code:

#!/bin/bash

while true
do
     if [[ $# -eq 0 ]] ; then
        if [[ $result == "" ]]; then # check if $result is empty
            echo Enter operand1 value: 
            read operand1
        else
            operand1=$result # if not empty then assign its value to $operand1
            echo "Operand 1 is: $result"
            echo ""
        fi
 
         # Offer choices
         echo 1. Addition
         echo 2. Subtraction
         echo 3. Multiplication
         echo 4. Division
         echo 5. Exit
 
         echo Enter your choice:
         read choice

         if [[ $choice != 1 && $choice != 2 && $choice != 3 && $choice != 4 && $choice != 5 ]] ; then
             echo Sorry $choice is not a valid operator - please try again 
             echo Enter your choice:
             read choice
         fi
 
         echo Enter operand2 value:
         read operand2
 
         # get operands and start computing based on the user's choice
         if [[ $choice -eq 1 ]] ; then
             result=$((operand1+operand2)) # store result
             echo ----------------------------------------
             echo Addition of $operand1 and $operand2 is $((operand1+operand2))
             echo ----------------------------------------
             echo
         elif [[ $choice -eq 2 ]] ; then
             result=$((operand1-operand2)) # store result
             echo ----------------------------------------
             echo Subtraction of $operand1 and $operand2 is $((operand1-operand2))
             echo ----------------------------------------
             echo
         elif [[ $choice -eq 3 ]] ; then
             result=$((operand1*operand2)) # store result
             echo ----------------------------------------
             echo Multiplication of $operand1 and $operand2 is $((operand1*operand2))
             echo ----------------------------------------
             echo
         elif [[ $choice -eq 4 && operand2 -eq 0 ]] ; then
             echo Can not divide by 0 please try again 
             echo Please enter operand2
             read operand2
             echo ----------------------------------------
             echo Division of $operand1 and $operand2 is $((operand1/operand2))
             echo ----------------------------------------
             echo    
             result=$((operand1/operand2)) # store result
          elif [[ $choice -eq 4 && operand2 -ne 0 ]] ; then
             result=$((operand1/operand2)) # store result
             echo ----------------------------------------
             echo Division of $operand1 and $operand2 is $((operand1/operand2))
             echo ----------------------------------------
             echo    
         elif [[ $choice -eq 5 ]] ; then
             exit    
         else
             echo ----------------------------------------
             echo Invalid choice.. Please try again
             echo ----------------------------------------
             echo
         fi        
   else
             echo ----------------------------------------
             echo You either passed too many parameters or too less
             echo than the optimum requirement.
             echo
             echo This program accepts a maximum of 2 arguments or no
             echo argument at all in order to run successfully.
             echo ----------------------------------------
   fi
done

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