Perl 学习手札之十三：building function-优快云博客

本文深入探讨了Perl编程中常用的功能函数，包括字符串操作、数字转换、数组处理及时间日期相关函数。通过具体示例展示了如何在实际编程中灵活运用这些函数，旨在提升Perl编程能力。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

string.pl

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

main( @ARGV);

sub main
{
     my $string = " this is a string\n ";
     print $string;

     chomp $string;
    message( " [$string] ");

     chop $string;
    message( " [$string] ");

     my $s2 = uc $string;
    message( $s2);

     $s2 = lc $string;
    message( $s2);

     $s2 = substr( $string, 5, 2);
    message( $s2);

     $s2 = substr( $string, 5, 4);
    message( $s2);

     $s2 = index ( $string, ' s ');
    message( $s2);

     $s2 = rindex( $string, ' s ');
    message( $s2);

     $s2 = substr( $string, rindex( $string, ' s '));
    message( $s2);
}

sub message
{
     my $m = shift or return;
     print( " $m\n ");
}

sub error
{
     my $e = shift || ' unkown error ';
     print( " $0: $e\n ");
     exit 0;
}

可以参考perldoc perlfunc 来查看所有的building function 的情况。

以上罗列了几个比较常用的。

number.pl

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

main( @ARGV);

sub main
{
     my $number = 123.456;
     my $n2 = int( $number);
    message( $n2);

     $number = " a5 ";
     $n2 = hex( $number);
    message( $n2);

     $number = " 75 ";
     $n2 = oct( $number);
    message( $n2);

     $number = rand();
    message( $number);

     $number = rand( 100);
    message( $number);

     $number = int( rand( 100));
    message( $number);

     srand($$. time);
     $number = int( rand( 100));
    message( $number);
}

sub message
{
     my $m = shift or return;
     print( " $m\n ");
}

sub error
{
     my $e = shift || ' unkown error ';
     print( " $0: $e\n ");
     exit 0;
}

关于数字的building in 函数不是太多

arrays.pl

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

main( @ARGV);

sub main
{
     my @list = qw(jan feb mar apr may june july aug sep oct nov dec);
     push( @list, ' foo ');    #将元素‘foo'加入数组的最后一行
    message( join( ' : ', @list));
    message( join( ' : ', reverse @list));#将数组求逆序

     my $string = pop @list;#输出数组的最后一个元素
    message( $string);

     $string = shift @list;#输出数组的第一个元素给string
    message( $string);

     unshift ( @list, $string);#将string加入数组，变成数组的第一个元素
    message( $string);

}

sub message
{
     my $m = shift or return;
     print( " $m\n ");
}

sub error
{
     my $e = shift || ' unkown error ';
     print( " $0: $e\n ");
     exit 0;
}

可以看相应的注释。

time.pl

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

main( @ARGV);

sub main
{
     my $t = time;
     my @months = qw(jan feb mar apr may june july aug sep oct nov dec);
     my ( $sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime();
     $year+= 1900;
    message( " year: $year, month:$months[$mon],day: $mday ");
    message( " $year-$months[$mon]-$mday $hour:$min:$sec ");
}

sub message
{
     my $m = shift or return;
     print( " $m\n ");
}

sub error
{
     my $e = shift || ' unkown error ';
     print( " $0: $e\n ");
     exit 0;
}

就一个关于localtime的building in function。