Shell编程-素数

此为以前写的代码，整理中，未完待续。

问题

判断用户输入任意数是否为素数

解决

#!/bin/bash
#judge that a number is prime
declare -i num
read -p "Please input a number": num
if [ "$num" -gt 2 ]
    then
       declare -i i=2
       c=$(( $num/2 ))
       while [ $i -lt $c ]
        do
          a=$(( $num%$i ))
          if [ "$a" -eq 0 ]
            then
               echo "the number $num is not prime!"
               exit 1
          fi
                  i=$(( $i+1 )) 
        done 
       echo "the number $num is prime!"
    else
      echo "Hi,the number $num is not prime!"
fi

分析

1. 判断语句：大于/小于
2. 循坏语句
3. 余数