本文介绍了变量乘法的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我正在编写一个脚本,为插入的数字提供阶乘,但是我在乘法时遇到了一些问题.

I'm making a script which gives the factorial for a inserted number, but i'm having some problems with the multiplication.

注意:阶乘为:9!= 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1

Note: the factorial for is given by: 9!=9*8*7*6*5*4*3*2*1

这是我的代码:

#!/bin/bash

echo "Insert an Integer"

read input

if ! [[ "$input" =~ ^[0-9]+$ ]] ; then
   exec >&2; echo "Error: You didn't enter an integer"; exit 1
fi

function factorial
{
while [ "$input" != 1 ];
do
    result=$(($result * $input))
    input=$(($input-1))
done
}
factorial
echo "The Factorial of " $input "is" $result

对于不同的乘法技术,它总是给我带来各种错误:/

it keeps giving me errors of all kinds for diferent multiplication technics :/

当前输出为:

joaomartinsrei@joaomartinsrei ~/Área de Trabalho/Shell $ ./factorial.sh
Insert an Integer
3
./factorial.sh: line 15: * 3: syntax error: operand expected (error token is "* 3")
The factorial of 3 is

非常感谢,最好的问候

Many Thanks,Best Regards

推荐答案

主要问题是,您永远不会初始化result(至1),因此:

The main problem is that you never initialize result (to 1), so this:

result=$(($result * $input))

等效于此:

result=$(( * $input))

这不是有效的算术表达式.

which is not a valid arithmetic expression.

这篇关于变量乘法的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

09-12 11:29