perl的array和map/hash

一 array

1）实例

use strict;
use warnings;

my @myarray = (123,"hello", 456, 'guy');

foreach(@myarray)
{
    print "$_ " ;
}
print "\n";
foreach my $item (@myarray)
{
    print "$item " ;
}
print "\n";
for(my $i = 0; $i <scalar(@myarray); $i++)
{
    print "$myarray[$i]" . " ";
}
print "\n";
for(0..($#myarray))
{
    print "$myarray[$_]" . " ";
}
print "\n";

@myarray = (@myarray, 789);
print "@myarray\n" ;
push(@myarray,"gril");
print "@myarray\n" ;
unshift(@myarray, '000');
print "@myarray\n" ;

delete $myarray[1];
print "@myarray\n" ;

2）函数，如下：

3）注释：

1】使用@定义array，使用array的item时$array[n]；

2】使用scalar来获得array的size；

3】$#获得最大的index，即size-1；

4】$_在for和foreach中表示当前item；

5】push/pop用来在array的最后加入和弹出item；

6】shift/unshift用来在array的前面删除和插入item；

7】split/john用来实现array和string间的转化；

8】delete可以用来删除item，例如delete $myarray[1];

二 map/hash

1) 实例：

use strict;
use warnings;

my %myhash = ('k1',100,'k2',200);
# my %myhash = (k1=>100,k2=>200);
print %myhash ;
print "\n";
$myhash{'k3'} = 300;
$myhash{'k4'} = 400;
print %myhash ;
print "\n";

foreach my $key (keys %myhash)
{
    print $key . " indexes ".$myhash{$key}."\n";
}
foreach my $value (values %myhash)
{
    print $value ."\n";
}
while((my $key, my $value)= each(%myhash))
{
    print "$key indexes $value \n"
}

if(exists $myhash{'k1'}) {print "k1 is exist\n";}

delete $myhash{'k1'};
print %myhash ;
print "\n" ;

2）函数，如下：

3）注释：

1】%用来定义map/hash；
2】对单个的key赋值是使用$,例如$myhash{'k3'} = 300;
3】keys获得所有的keys到array；
4】values获得所有的values到array；
5】迭代，每次返回一对key/value;
6】exists用来判断某个key是否存在；
7】delete用来删除指定的key，同时对应的value也被删除；

三 总

Array Functions

@array = ( ); Defines an empty array

@array = (“a”, “b”, “c”); Defines an array with values

$array[0] The first element of @array

$array[0] = a; Sets the first element of @array to a

@array[3..5] Array slice - returns a list containing the 3rd thru 5th

elements of @array

scalar(@array) Returns the number of elements in @array

$#array The index of the last element in @array

grep(/pattern/, @array) Returns a list of the items in @array that matched

/pattern/

join(expr, @array) Joins @array into a single string separated by expr

push(@array, $var) Adds $var to @array

pop(@array) Removes last element of @array and returns it

reverse(@array) Returns @array in reverse order

shift(@array) Removes first element of @array and returns it

sort(@array) Returns alphabetically sorted @array

sort({$a<=>$b}, @array) Returns numerically sorted @array

Hash Functions

%hash = ( ); Defines an empty hash

%hash = (a => 1, b=>2); Defines a hash with values

$hash{$key} The value referred to by this $key

$hash{$key} = $value; Sets the value referred to by $key

exists $hash{$key} True if the key/value pair exists

delete $hash{$key} Deletes the key/value pair specified by $key

keys %hash Returns a list of the hash keys

values %hash Returns a list of the hash values 

完！