Perl基本语法实例，变量，数组，函数，if, for, while

#!/usr/bin/perl -w

#########################################################################

# File Name: test.pl

#########################################################################

print "hello word \n";

print "---- 变量定义用\$ 符号------\n";

$a=`echo xxxx`;

print "$a";

$b='aaaa'.'hhhh';

$c="bbbb";

$d="$b"."$c";

$d.='eeee';

print "$d\n";

print "d: $d\n";

$bl1 = 1>=0;

$bl2 = 1>=3;

print $bl1;

print $bl2;

print "---- if elsif else 条件判断语句 ----\n";

$if1=2;

if($if1 == 1){

print "pass\n";

}elsif($if1 == 2){

print "==2\n";

}else{

print "fail\n";

}

#chomp($in1 = <STDIN>);

#print "your input: $in1\n";

#if(defined($in2)){

# print "1";

#}else{

# print "2";

#}

print " ------- \@ 符号来定义数组 ------ \n";

@array = (1,2,3,"4")x4;

print "$array[1]\n";

print "$#array\n";

print "$array[-1] \n";

$xtest="123"x5;

print "$xtest\n";

print "pop push 针对数组的末尾操作 \n";

print "pop 取出最后一个，返回数组剩下的， push将一个元素添加到末尾 \n";

print "shift unshift 为 pop push的反向操作，针对数组头\n";

@array2 = 5..10;

print "$#array2 ---- $array2[-1] \n";

pop @array2;

print "$#array2 ---- $array2[-1] \n";

pop(@array2);

print "$#array2 ---- $array2[-1] \n";

print "---------- array3 ----------\n";

@array3 = 1..3;

print "$#array3 ---- $array3[-1] \n";

push @array3,9;

print "$#array3 ---- $array3[-1] \n";

push @array3,10...12;

print "$#array3 ---- $array3[-1] \n";

print "---------- array4 ----------\n";

@array4 = 1..3;

print "@array4 ---- $array4[0] \n";

shift @array4;

print "@array4 ---- $array4[0] \n";

unshift @array4,99;

print "@array4 ---- $array4[0] \n";

unshift(@array4,'98');

print "@array4 ---- $array4[0] \n";

print "---------- array5 ----------\n";

@array5 = qw(eating rocks is wrong);

$array5 = "right";

print "@array5 ... $array5 \n";

print "this is $array5[3] \n";

print "this is ${array5}[3]\n";

print "this is $array5"."[3]\n";

print "this is $array5\[3] \n";

print "--------- for --------------\n";

for($i=0; $i<10; $i++){

print "for: $i\n";

}

#实际for和foreach是一样的

#中断循环对比C 的break和continue，Perl分别对应的是 last 和 next

#Perl中还特有 redo, 调到当前循环的顶端，不进行条件判断就再次执行本次循环

#next会进入下一次循环，redo会继续执行本次循环

print "--------- foreach ----------\n";

@rocks = qw(bedrock slate lava);

print "before rocks: \n @rocks \n";

foreach $rock (@rocks){

#如果有 redo 应该跳到的位置

$rock = "\t$rock";

$rock .= "\n";

print "new rock: $rock \n";

}

print "after rocks: \n @rocks \n";

print "--------- reverse 翻转 ----------\n";

@reverse1 = reverse 6..9;

print "@reverse1 \n";

@reverse2 = reverse @reverse1;

print "@reverse2\n";

print "--------- sort 排序 -------------\n";

@sort1 = qw(aaa ccc eee bbb ddd);

print "@sort1\n";

@sort1 = sort(@sort1);

print "@sort1\n";

print "--------- context -----------\n";

print "变量和列表会根据上下文给出不同的值\n";

print 1+@sort1."\n";

@rocks = qw(xxx aaa ccc);

print "I have",@rocks,"rocks!\n";

#强制转换为标量

print "I have", scalar @rocks, "rocks!\n";

print "--------- sub ----------------\n";

sub subtest1{

$temp=$a.$b;

$temp;

}

$a = "1";

$b = "2zzzzz";

$c = &subtest1;

print "c: $c\n";

sub addfunc{

$size = @_;

print "param size: $size\n";

my($num1, $num2);

($num1, $num2) = @_;

$num1 + $num2;

}

$addresult = &addfunc(100,99);

print "addresult: $addresult\n";

print "-------- 子程序 == 函数 ----\n";

print "函数参数放在 \@_数组内，可以用shift循环的切出第一个参数\n";

print "my() 定义局部变量\n";

print "子程序的返回值就是最后一部的计算值\n";

sub max{

my($maxValue) = shift @_;

foreach(@_){

if($_>$maxValue){

$maxValue = $_;

}

}

$maxValue;

}

@numset = (100,600,3000,3001);

$maxValue = &max(@numset);

print "maxValue: $maxValue\n";

sub which_element_is{

if(@_ < 2){

return "输入参数个数不能小于2";

}

my($what, @array) = @_;

my $index = 0;

foreach(@array){

if($what eq $_){

#判断字符串相等不能使用==，只能用eq

print "Find this element [$_]: $index\n";

return $index;

}

$index++;

}

return "can't find this element";

}

@names = qw(kevin xiang jie);

$which_element = &which_element_is("jie", @names);

print "which_element: $which_element\n";

print "上面的程序都是不严谨语法， 开头添加 use strict 变为严谨语法检测\n";

print '定义变量时需要用my定义, my $baa = 1; '."\n";