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.
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