perl 学习笔记(3)

其他函数和运算符

在本章中学习：(1)如何对标量进行简单的字符串搜索 (2)如何进行字符替换 (3)如何使用print函数 (4)如何将数组用作堆栈和队列

一、搜索标量

?用index进行搜索

index string,substring

index("Pocket full of posies","ket")??????????? #?return 3

$a="Ashes,ashes,we all fall down";

index($a,"she");????????????????????????????????????????? #return 1

index($a,"they")???????????????????????????????????????? #return -l??? (not found)

可以给index函数规定一个字符串中开始进行搜索的起始位置，如下例子

$reindeer="dasher dancer prancer vixen";

index($reindeer,"da")??????????????? #return 0

index($reindeer,"da",1)????????????????#return??7

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二、功能更强的print函数

printf? formatstring,list

print? filehandle? formatstring,list

printf函数的部分域说明：c? 代表字符??? s 代表字符串??? d? 代表十进制整数?? f? 代表浮点数

域说明符的格式是% -w.dx??

w是域需要的总宽度? x表示输出的是数据类型。其中%和x是不可少的

d代表保留小数点的位数。

printf("%20s","Jack")????????#? print "????????????????????? Jack"

printf("%-20s","Jill")???????? # print "Jill???????????????????????? "

$amt=7.12;

printf("%6.2f",$amt)??????????? #print "??? 7.12"

$amt=7.127;

printf("%6.2f",$amt)??????????? #print "???????7.13"

$amt=5.6;

printf("%6.2f",$amt)????????????? #print "???????? 5.60";

printf("%6d",$amt)?????????????? #print "?????? 5"

?

#! /usr/bin/perl
use warnings;
use strict;

my @arr;
while(<DATA>) {
?? chomp;
?? @arr=split;
?? printf "%-50s%-20sn",$arr[0],$arr[1];
?? print "===============================n";
}

__DATA__ PRODUCT:NLSRTL VERSION:19.2.0.1 PRODUCT:PL/SQL VERSION:10.2.3.1 ~????????????????????????????????