Perl 特性之不安全的依赖
最近写 Perl 程序时遇到一个很奇怪的问题: Insecure dependency in unlink while running with -T switch at ../tmpfile.pl line 44. 经过检查,发现这是 Perl 语言一个特性,在运行时使用 -w 或 -T 都意味着 “万无...
最近写 Perl 程序时遇到一个很奇怪的问题: Insecure dependency in unlink while running with -T switch at ../tmpfile.pl line 44. 经过检查,发现这是 Perl 语言一个特性,在运行时使用 -w 或 -T 都意味着 “万无...
当 python 需要调用 C 程序,或是进行文件、网络操作时,需要对二进制结构化字节流进行处理,此时需要使用到 struct 这个模块提供的方法。 详细方法可以查看 官方教程...
结论 $var//=2:等价于 defined($var)||2,即 未定义 时才赋值为 2 ,否则不变( 即使是 0或 空字符串 ) $var||=2 :除非定义且为 true 才不会赋...
-r: File is readable by effective uid/gid. -w: File is writable by effective uid/gid. -x: File is executable by effective uid/gid. -o: File is owned by effective uid. -R: File is readable by real uid/gid. -W: File is writable by real uid/gid. -X: File is executable by real uid/gid. -O: File is owned by real uid. -e: File exists. -z: File has zero size (is empty). -s: File has nonzero...
在调试 Perl 程序时常常需要打印哈希表内容,虽然可以直接使用 foreach 打印,但数据复杂了就难办了,此时可以将 Hash 表转换为 json 文本再打印: use JSON; my $data = {'info'=> "test", 'struct' => {'test1'=>'test1', 'test2'=>'test2'}};...