(22)--5.4 循环结构-美化整理0826.ppt

CONTENTSforfor循环语句循环语句whilewhile循环语句循环语句for循环语句for循环语句循环语句u语法一 for(变量赋值;条件判断;变量迭代)do 语句块1 done注：注：for语句中一定语句中一定要要以以do开始开始及及以以done结尾！结尾！for循环语句循环语句u举例编写一个for循环，输出0-4共5个数值.#!/bin/bash for(i=0;i5;i+)do echo$i,is a number.done输出结果：0,is a number.1,is a number.2,is a number.3,is a number.4,is a number.for循环语句循环语句u举例编写一个程序，能在当前目录下创建10个以数值0-9为前缀，以.sh为扩展名的文件#!/bin/bash for(i=0;i10;i+)do touch$i.sh donefor循环语句循环语句u举例编写一个程序，打印乘法公式#!/bin/bash for(i=1;i10;i+)do for(j=1;j=i;j+)do echo-n“$j*$i=$($i*$j)“if$i-eq$j then echo$n fi done donefor循环语句循环语句u语法二 for var in item1 item2 itemN do 语句块1 done注：注：注意注意in的用法的用法for循环语句循环语句u举例编写一个for循环，变量的取值列表为：dog cat lion tiger，输出结果为：#!/bin/bash for animal in dog cat lion tigerdo echo“There are$animals.”doneThere are dogs.There are cats.There are lions.There are tigers.for循环语句循环语句u举例#!/bin/bash for animal in dogs cats father lion tigerdo echo“There are$animals.”doneThere are dogs catss.There are fathers.There are lions.There are tigers.for循环语句循环语句u举例#!/bin/bash for animal in dogs“cats father”lion tigerdo echo“There are$animals.”doneThere are dogss.There are cats fathers.There are lions.There are tigers.for循环语句循环语句u举例取值列表是变量list=“beijing tianjing shanghai guangzhou”list=$list”xizang”for scenery in$listdo echo“Have you visited$scenery?”doneHave you visited beijing?Have you visited tianjing?Have you visited shanghai?Have you visited guangzhou?Have you visited xizang?for循环语句循环语句u举例取值列表是存在文件中for scenery in$(cat place.txt)do echo“Have you visited$scenery?”doneHave you visited beijing?Have you visited tianjing?Have you visited shanghai?Have you visited guangzhou?Have you visited xizang?beijing tianjing shanghai guangzhou xizangplace.txtwhile循环语句while循环语句循环语句u语法语句格式：while 条件判断式 do语句块1done当条件成立时，执行循环一般一句一行，同行多个命令可使用分号或空格键隔开。while循环语句循环语句u举例当用户输入break或者BREAK才结束程序执行，否则就一直告知用户输入字符串，并将用户输入字符串输出。#!/bin/bashwhile$yn!=“break-a$yn!=“BREAK doread-p“Please input a string:(break/Break to stop)ynecho You input a string:$yndoneecho OK!you interrupt the program.while循环语句循环语句u举例编写一猜字游戏，当用户输入指定的字符串后才结束游戏，否则就一直告知用户再试一次。while循环语句循环语句1#!/bin/bash2 while true3 do4 read-p$Guess wordn(Tips:The word consists of four blocks,the first word is“g”,the last word is“d”)n word5 if$word!=“good”6 then7 echo“Try again!”8 else9 echo“Bingo,you are right!”10 break11 fi12 done总结总结forwhile循环结构THANKS谢谢 谢谢 聆聆 听听