The implementation of Shell grammar exercises simple Calculator

Tag:expression    calculator    calculator   

#!/bin/bash# by inputting data   calculating results expression= '; calculator () {    echo  "Please enter a number:";     read x;    echo  "Please enter another number:";     read y ;    echo  "Please enter operation symbol:";     read symbol;   case   $symbol  in            +)                ret= ' expr  $x  +  $y ';              expression= "$x + $y";              ;;                          -)               ret= ' expr  $x  -  $y ';               expression= "$x-$y";             ;;           \*)              ret= ' expr  $x  \*  $y ';             expression= "$x * $y";             ;;          /)            ret= ' expr  $x  /  $y ';           expression = "$x/$y";          ;;         %)              ret= ' expr  $x  %  $y ';              ;; esac;return  $ret;} while :   do      echo  "Start calculation: Y/N:";      read -n1 flg;     case  $FLG  in          n| N)              echo  ' calculation terminated ';              break;                 ;;        y| Y)           ;;     *)        echo  ' compute terminated ';        break;       ;; esac;     # if [[  $flg  ==   "N"  ]]     # then    #     echo  ' compute terminated ';    #      break;    # fi;     calculator;    res=$ ?    echo -e  "Operation result is: ${expression}= $res \ n";d one

Record the shell to achieve a simple calculator effect, run the effect:

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The implementation of Shell grammar exercises simple Calculator