学习笔记-Perl-记录最简单的一些实例-1

#Example1      #while循环
#!/usr/bin/perl

use 2.010; #声明本校本所使用的版本号

while(<>){  #接收键盘的任意输入
chomp;
print join("\t",(split /:/)), "\n"; 首先用':'分隔字符串，然后用'\t'(制表符)连接
}

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#Example2      #函数
#!/usr/bin/perl
@lines = `perldoc -u -f atan2`;
foreach (@lines) {
 s/\w<([^>]+)>/\U$1/g;
 print;
}

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#Example3     #真正的第一个可以运行的东东，只输出一句话
#!/usr/bin/perl

printf ("%s","hello"." "."word\n");  #格式控制(%s)只对printf有效  
print ("%s","hello"." "."word\n");   #格式控制(%s)被当做字符输出
print "hello\ word\!\n";   #括号可以删除掉的
print "hello word!\n";     #空格和叹号的转义也可以删掉
print ("%s","hello"," ","word\n");    #下面四个的输出完全一样
print ("%s"."hello"." "."word\n");
print "%s","hello"," ","word\n";
print "%s"."hello"." "."word\n";
say "%s"."hello"." "."word\n"; #这个也是输出一句话，不过要求版本最低是5.010

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#Example4     #接收输入参数
#!/usr/bin/perl

$line = ;
if ($line eq "\n"){     #如果只有一个回车
 print "That was just a blank line!\n";    
} else {
 print "That line of input was: $line";
}

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#Example5        #见识一下perl里的赋值操作
#!/usr/bin/perl

print "5" x 4;   #输出4个5
print "\n";      #输出一个回车

print "yu_qq" x (4+1);   #输出( 4+1)=5遍的yu_qq
print "\n";      

$lin = "abc" ;
$ll = "f";
$lin .= "d";     #'.'连接字符串，和JAVA中的'+'相同，把d加到$lin(abc)后面
$lin = $ll . $lin;    #把两个($ll和$lin)连在一块儿
print "$lin";    
print "\n";

$num= "5" x 4;   
print "$num\n";
$num -= 5500;      #双目操作运算，连在一起简写了
print "$num\n";    
$num *= $num;      
print "$num\n";

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#Example6        #数组(i堆栈)
#!/usr/bin/perl

@arry = qw/ a1 a2 b3 c4 d5 d6/;   #声明一个堆栈
print "@arry" . "\n";    
@ff = pop(@arry);        #出栈(最后一个d6)
print "@ff" . "\n";
print "@arry" . "\n";   
push(@arry, b6,d7);      #入栈把b6和d7压进去(在结尾)
print "@arry" . "\n";

@ff = shift(@arry);      #出栈(第一个a1)
print "@ff" . "\n";      #
print "@arry" . "\n";
unshift(@arry, d1,c1);   #入栈把d1和c1压进去(在开头)
print "@arry" . "\n";

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#Example7        #foreach 循环
#!/usr/bin/perl

foreach (1..10) {
 print "I can count $_!\n";  # $_ perl内置变量 
}

foreach $rack (qw/ 1 2 3 10/) {    #也可以指定变量$rack，循环控制参数qw/ 1 2 3 10/
 print "I can count $rack!\n";
}

@rack= qw/ 110 11 we esfd ef/;    #还可以使用数组@rack
foreach $rack (@rack) {
 print "I can count $rack!\n";
}

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#Example8           #标量与列表及其上下环境
#!/usr/bin/perl

@rock = qw( tals dfkl dj yu sj );    #某种程度上可以简单理解为@是列表(数组、堆栈...)，$是标量(变量、字符串、数字、Boolean...)
$rock = @rock;           #取@rock列表长度
print "@rock" . "\n";    #输出列表@rock
print @rock;             #去除中间空格输出@rock
print @rock . "\n";      #输出@rock的长度
print $rock . "\n";      #输出@rock的长度
print "$rock" . "\n";    #输出@rock的长度
print scalar @rock;      #输出@rock的长度

@ar = ("1542","123","0452");    #这种写法和qw//一样的
$ar = scalar @ar;        #取@ar列表长度
print "@ar\n";           #输出列表@ar
$ar += 67;         #对$ar进行加法操作
print "$ar\n";           #输出$ar的值
@ar = sort @ar;          #对@ar进行排序(不是按照数值大小，而是按照ASCII码排序)
print "@ar\n";           #输出列表@ar
print @ar;               #

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#Example9        #子程序的调用
#!/usr/bin/perl -w       #输出警告信息

sub sum {                #定义子程序sum,该程序将会被覆盖
  print "I'm sub_sum!\n";     #表明身份
  $ff + $dd;             #将计算$ff和$dd的和作为子程序的返回
}

$ff = 3;       
$dd = 5;
$aa = ∑            #调用子程序sum，并将其返回值赋值给$aa
print "\$SUM is $aa.\n";  #输出结果
print "\$ff is $ff.\n";

sub sum {                   #重新定义子程序sum,该子程序将覆盖上面的sum
  $ff = $ff + $dd;          #计算$ff和$dd的和，赋值给$ff
  $ff + $dd;            #计算$ff和$dd的和，这个语句不是最后一条，
                #执行结果不会作为子程序的返回，计算结果会被抛弃
  print "I'm sub_sum!\n";   #print 语句执行的结果作为返回值(如果没有后面这句)
  $ff = $ff + $dd;          #将$ff和$dd的和相加后赋值给$ff，并将后来的$ff作为返回值
}

$aa = 3 * ∑ #调用子程序sum     #调用子程序sum，并将其返回值赋值给$aa
print "\$SUM is $aa.\n";       #输出结果
print "\$ff is $ff.\n";

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#Example10       #哈希数据

#!/usr/bin/perl

$family_name{"fred"} = "yu";
$family_name{"yu"} = "QQ";
$family_name{"QQ"} = "yu";

foreach $person (qw< fred yu QQ >) {
 print "I've heard of person $family_name{$person}.\n";
}

$foo = "Q";
print $family_name{ $foo . "Q" }."\n";