渴死的火烈鸟

今天写code一个体会就是写出好的SQL很重要。。。 1. 不要用not in，严重影响performance，用其他写法替代。2. 注意left join，join等区别。3. 。。。 还有就是perl的一个问题一个undef的值跟其他数值比较结果如何？比如 $var = undef;if($var <= 0){ print "here";}...

Today in a small project I need to serialize a perl class object to string in order to cache it. And when getting back the value from the cache I need to deserialize it to original class objects. ...

q// is generally the same thing as using single quotes - meaning it doesn't interpolate values inside the delimiters.qq// is the same as double quoting a string. It interpolates.qw// return a list...

我前面写过一种方法生成全排列,现在看用DP的方法解决。参考[url="http://standalone.iteye.com/blog/757948"]How to generate permutations[/url] 看前面的那种解法。DP的思路就是生成N个数的全排列，先考虑生成前面N-1个数字的全排列，然后把最后一个数字插入上一步每个结果的每个缝隙中，形成最后的结果。用pe...

[list][*][b]生成连续的一列数字或字母:[/b]my @numbers = (1..100);my @chars = (a..z);[*][b]添加或者删除元素[/b]shift: 移除数组的第一个元素；unshift: 添加一个元素到数组的最后；push: 添加一个元素到数组的第一个元素；pop：去除数组的最后一个元素。[ta...

假设有25美分，10美分，5美分，1美分的硬币足够多，假设有N美分钱，问你怎么用这些硬币表示？用perl重新做这个问题，前面用[url="http://standalone.iteye.com/admin/blogs/1670164"]java[/url]做过[code="java"]use strict;use warnings;my $count = 0;s...

处理perl参数的时候最有用的模块，有关使用具体细节参考以下别人的博客：[url]http://www.php-oa.com/2009/04/04/perl_getopt-long.html[/url]

每次使用DBI的时候都忘记该使用哪个函数，下面这个博客讲得很详细！[url]http://blog.youkuaiyun.com/fan_zhen_hua/article/details/6078337[/url]

[url]http://www.perlmonks.org/index.pl?node_id=287647[/url]open FILEHANDLE, 'somefile.txt' or die $!;my $string = do { local $/; };The above idiom is a consise way to "slurp" the entire con...

[url]http://www.perlmonks.org/?node_id=57193[/url]system("wc -l");Will call the given command and return the return value of that command. This is usually not what you want, because most of the ...

If you are also confused about what benefits prepare_cached will bring to you like me, please read this article.[url]http://gssg-www.stanford.edu/public/preparecached.html[/url]

Look at this example: [url]http://stackoverflow.com/questions/125171/passing-a-regex-substitution-as-a-variable-in-perl[/url]

看了一下下面这篇文章，理解了our变量的意思。[url]http://www.chinaunix.net/jh/25/556778.html[/url]

1. 用eval获得程序的执行错误$a = 10;$b = 0;$c = $a/$b;会发生什么？程序会crash,因为有浮点数异常。用eval就可以做到两全，既执行语言，又能在出现异常的时候不crash$a = 10;$b = 0;eval {$c = $a/$b};eval { ... }可以捕获执行的多条语句的错误结果。然后用$@可以得到错误原因。...

built-in data types: scalar: int, string, referencearrayhash

http://www.devshed.com/c/a/Perl/File-Tests-in-Perl/ File test in perl is quite useful. E.g., how to check if a file exists? How to check if it's writable? And how to get age of a file? I fin...

http://www.perlhowto.com/executing_external_commands

Submitted by alvin on August 9, 2009 - 8:41pmtags: args arguments argv command line perl perl read source code Perl command line FAQ: How do I read command-line arguments with Perl (command lin...

1 my $string = '"hello there", said Pooh, "how are you today?". I said "brilliant!".'; 2 print "$string\n"; 3 $string =~ s/('|")(.*?)\1/$1.uc($2).$1/ge; 4 print "$string\n"; I want to.

http://www.php-oa.com/2009/09/09/perl-poe-1.html

Today I encounter a problem when sending html content via Perl's MIME:Lite, in my html there is always a </tr> got broken...damn it! I checked the html string, it's all right. Finally I foun...

这个文章讲得很好。[url]http://perlmeme.org/tutorials/writing_test_harness.html[/url]

几种我所用到的用来处理日期，时间的函数总结。[u][b]Perl[/b][/u]1. localtime[code="perl"] # 0 1 2 3 4 5 6 7 8 ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);[/code]I...