[转 改] Perl初级教程 （二）

【对于字符串】

$b = 'BB';
$c = 'CC';
$a = 'AA';

$a = $b . $c; 　　# Concatenate $b and $c = BBCC
$a = $b x $c; 　　# $b repeated $c times

【Perl的赋值语句】

$a = $b; 　　　　　# Assign $b to $a
$a += $b; # Add $b to $a　　（算数运算）
$a -= $b; # Subtract $b from $a
$a .= $b; # Append $b onto $a （字符运算）

【 互操作性】

$b = 'Pear';
$c = 'CC';
$a = 'Apple';

print $a.' and '.$b; 
print "\n";　　　　# 制表符（\t） 换行（\n）
print '$a and $b';
print "\n";
print "$a and $b";

【数组变量】

数组通过以0开始的索引进行访问，方括号内为索引值

@List = ("1",2,'3');

print @List;

> 123

【 数组 赋值/删减】 

@List = ("1",2,'3',"Array");

@array = (5..15);   #序列化列表5~15;

print @List;

print "\n";

print @array;

>123Array

  56789101112131415

# push Statement.

push(@List,"Added");

print @List;

print "\n";

push(@List,@array);

print @List;

>123Array

  123Array56789101112131415

# pop Statement.

@List = ("1",2,'3',"Array");
@array = (5..15);
push(@List,@array);
$e =  pop(@List);
$f =  pop(@List);

print $f;
print "\n";
print @List;
print "\n";
$f = @List;
print $f;

> 14

   123Array568910111213

   13

 # 数组也可以用来为多个标量进行赋值

@List = ("1",2,'3',"Array");
@array = (5..15);
push(@List,@array);
$e =  pop(@List);
$f =  pop(@List);
print "\n";
print $e;
print "\n";
print $f;
print "\n";

($e,$f,$a) = @List;      # 按照数组顺序项给变量赋值。

print "\n";
print $e;
print "\n";
print $f;
print "\n";
print $a;

> 15

   14

   1

   2

   3

# 最后，你可能想知道列表中最后一个元素的索引值，可以用这个表达式：

print $#List;

> 12;

 ($a, $b) = ($c, $d); # Same as $a=$c; $b=$d;
($a, $b) = @food; # $a and $b are the first two items of @food.
($a, @somefood) = @food; # $a is the first item of @food ， @somefood is a list of the others.
(@somefood, $a) = @food; # @somefood is @food and $a is undefined.