Bash CLI计算器计算结果异常问题求助

我用Bash编写了一款依赖bc工具的CLI计算器，但出现多处问题：

• 计算1.2+1.2得到结果4
• 计算-1*-1得到结果65025
• 输入小数时触发numeric argument required参数错误提示

已尝试修改返回值传递方式，改为通过输出传递数值，但仍需进一步排查问题。

原脚本代码 #

主脚本 #

#!/bin/bash

source utilities/menu.sh
source utilities/input_validation.sh

header="Choose from the options below(Example: 1, 2, 3 etc...):"
options=("1" "2" "3" "4" "5")
option_descriptions=("Add" "Subtract" "Multiply" "Divide" "Exit")
prompt="> "

calculate(){
  if [[ $option == "1" ]]
  then
    echo "$num1 + $num2" | bc
  elif [[ $option == "2" ]]
  then
    echo "$num1 - $num2" | bc
  elif [[ $option == "3" ]]
  then
    echo "$num1 * $num2" | bc
  elif [[ $option == "4" && $num2 != "0" ]]
  then
    echo "scale=2; $num1 / $num2" | bc
  elif [[ $option == "4" && $num2 == "0" ]]
  then
    echo "Dividing by 0 is undefined"
  else
    exit=0
  fi
}

calculator(){
  persistant_get_menu_option "$header" "$options" "$option_descriptions"
  option=$?
  if [[ $option == "5" ]]
  then
    return 1
  else
    persistent_get_number "$prompt"
    num1=$?
    persistent_get_number "$prompt"
    num2=$?
    echo "------------------------------------"
    calculate "$option" "$num1" "$num2"
    echo "------------------------------------"
    return 0
   fi
}

will_exit="0"
while [[ $will_exit == "0" ]]
do
  calculator
  if ! [ $? = 0 ]
  then
    will_exit="1"
  else
    will_exit="0"
  fi
done

echo "Good bye"

工具脚本：utilities/menu.sh #

#!/bin/bash

is_option(){
  for option in "${options[@]}"
  do
      if [ "${option}" = "$choice" ]
      then
          return 0
      fi
  done
  return 1
}

persistant_get_menu_option(){
  choice=""
  will_exit="0"
  while [[ $will_exit == "0" ]]
  do
    echo ""
    echo "$header"
    echo "-----------------------------------------------------------"
    i=0
    for description in "${option_descriptions[@]}"
    do
      echo "${options[i]}: $description"
      i=$((i + 1))
    done
    echo ""
    read -r choice
    is_option "${options[@]}" "$choice"
    if [[ $? == "1" ]]
    then
      echo "You must choose from the options given"
    else
      will_exit="1"
    fi
  done
  return "$choice"
}

工具脚本：utilities/input_validation.sh #

#!/bin/bash

is_numerical(){
  if ! [[ $user_input =~ (^-?0\.[0-9]*[1-9]+[0-9]*$)|(^-?[1-9]+[0-9]*((\.[0-9]*[1-9]+[0-9]*$)|(\.[0-9]+)))|(^-?[1-9]+[0-9]*$)|(^0$){1} ]]
  then
    return 0
  else
    return 1
  fi
}

persistent_get_number(){
  user_input=""
  will_exit="0"
  while [ $will_exit == "0" ]
  do
    echo "$prompt"
    read -r user_input
    is_numerical "$user_input"
    if ! [ $? = 0 ]
    then
      echo "Input must be numerical"
    else
      will_exit="1"
    fi
  done
  return "$user_input"
}

报错示例 #

计算1.2+1.2时的报错 #

1
>
1.2
utilities/input_validation.sh: line 27: return: 1.2: numeric argument required
>
1.2
utilities/input_validation.sh: line 27: return: 1.2: numeric argument required
------------------------------------
4
------------------------------------

计算-1*-1时的报错 #

> 
-1
> 
-1
------------------------------------
65025
------------------------------------

更新：修改返回值传递方式 #

尝试将calculator和persistent_get_number函数改为通过输出传递数值，替代原来的返回值传递：

修改后的calculator函数 #

calculator(){
  persistant_get_menu_option "$header" "$options" "$option_descriptions"
  option=$?
  if [[ $option == "5" ]]
  then
    return 1
  else
    echo "> "
    num1=$(persistent_get_number)
    echo "> "
    num2=$(persistent_get_number)
    echo "------------------------------------"
    calculate "$option" "$num1" "$num2"
    echo "------------------------------------"
    return 0
   fi
}

修改后的persistent_get_number函数 #

persistent_get_number(){
will_exit="0"
  while [ $will_exit == "0" ]
  do
    read -r user_input
    is_numerical "$user_input"
    if ! [ $? = 0 ]
    then
      echo "Input must be numerical"
    else
      will_exit="1"
    fi
  done
  echo $user_input
}

内容的提问来源于stack exchange，提问作者Daniel