005#验证整数输入

验证整数输入，注意整数包含正负整数。

#!/usr/bin/env bash

validint(){
  number=$1
  min=$2
  max=$3

  # 空值检测
  if [ -z $number ]; then
    echo "You didn't input anything." >&2
    return 1
  fi

  # 负数符号检测
  if [ "${number%${number#?}}" = "-" ]; then
    num="${number#?}"
  else
    num="${number}"
  fi
  
  # 检查除负数符号后的数字是否是整数
  nodigits=$(echo $num | sed 's/[[:digit:]]//g')
  if [ ! -z "$nodigits" ]; then
    echo "Invalid number format. Only digits, no commas, spaces, etc." >&2
    return 1
  fi

  # 判断输入值是否小于指定最小值
  if [ ! -z $min ]; then
    if [ $number -lt $min  ]; then
      echo "You value is too small. the smallest value is $min" >&2
      return 1
    fi
  fi

  # 判断输入值是否大于指定最大值
  if [ ! -z $max ]; then
    if [ $number -gt $max ]; then
      echo "You value is too big. the largest value is $max" >&2
      return 1
    fi
  fi

  return 0
}

# 验证输入
if validint $1 $2 $3; then
  echo "Input is valid integer within your constraints."
fi