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Unicode defines several control characters from ASCII. http://www.unicode.org/charts/PDF/U0000.pdf I see many control characters are widely used but I really don't see where "information separators" are used. (U+001C~U+001F) What are them? What's the history of them? Where did they used for? Jonas Elfström Lammert Bies explains both their usage and the history behind. 28 – FS – File separator The file separator FS is an interesting control code, as it gives us insight in the way that computer technology was organized in the sixties. We are now used to random access media like RAM and magnetic

In my git workflow we have one main repository and one branch, master. Everyone pulls from remote master and everyone pushes to remote master. I want to work in my own branch while I prepare a feature. So far my history is something like this: git pull --rebase git checkout -b new_feature <make some commits> git checkout master git pull --rebase Now I want to merge the branch and here's what I need: No merge commits in my local master branch. All commits made into my new_feature branch merged into master as if I had made them in master. All merged commits to be merged somewhere on top of my

Traditional assembler, and higher level compilers work with several memory segments , according to intended use. Hence, there is a data segment, a stack segment, a bss, and text segment. The text segment is also called the code segment. Text segment? For machine code ? I have asked all the old-timers I could find, how something as unreadable as machine code came to be know as the "text segment". Every one of them agreed that, that was really what it was called, but none of them seemed to be surprised by it. And no one could offer an explanation. Here's your chance to show off your geek history

转自： https://www.cnblogs.com/youyoui/p/7851007.html 当需要从数据库查询的表有上万条记录的时候，一次性查询所有结果会变得很慢，特别是随着数据量的增加特别明显，这时需要使用分页查询。对于数据库分页查询，也有很多种方法和优化的点。下面简单说一下我知道的一些方法。 准备工作 为了对下面列举的一些优化进行测试，下面针对已有的一张表进行说明。 表名：order_history 描述：某个业务的订单历史表 主要字段：unsigned int id，tinyint(4) int type 字段情况：该表一共37个字段，不包含text等大型数据，最大为varchar(500)，id字段为索引，且为递增。 数据量：5709294 MySQL版本：5.7.16 线下找一张百万级的测试表可不容易，如果需要自己测试的话，可以写shell脚本什么的插入数据进行测试。 以下的 sql 所有语句执行的环境没有发生改变，下面是基本测试结果： select count(*) from orders_history; 返回结果：5709294 三次查询时间分别为： 8903 ms 8323 ms 8401 ms 一般分页查询 一般的分页查询使用简单的 limit 子句就可以实现。limit 子句声明如下： SELECT * FROM table LIMIT

Right click an arbitrary existing project in Package Explore, choose "export..." - "Java" - "Runnable JAR file", I find all the old projects in the "launch configuration" list. Those projects have already been removed from the disk, and are not visible in the Package Explore. How can I remove them from that list? I'm using eclipse indigo. benzonico Under Window...Preferences...Run/Debug...Launching...Launch Configurations, you can activate and deactivate some filters that restrict what is shown in Run...Run Configurations. I think it is what you are looking for. This question seems to be well

I'm dealing with some GB-sized numpy arrays in IPython. When I delete them, I definitely want them gone, in order to recover the memory. IPythons output cache is quite annoying there, as it keeps the objects alive even after deleting the last actively intended reference to them. I already set c.TerminalInteractiveShell.cache_size = 0 in the IPython configuration, but this only disables caching of entries to _oh , the other variables like _ , __ and so on are still created. I'm also aware of %xdel , but anyways, I'd prefer to disable it completely, as I rarely use the output history anyways, so

So two questions. How does angular applications handle refresh page, b/c from what I heard, $rootScope destroy() on refresh and application gets re-run and re-config -ed, and I was wondering if there's an elegant way to preserve the $rootScope without having to store $rootScope variables as a string into a storage. If I load a template on a directive that loads a modal on the page, is it possible to configure history to not navigate but to revert the open modal. and due to validations and such, I do not think it is possible to implement same function using href. If your url's are mapped with

What's the story behind our massive repitition of ./foo and cd .. . Where do these two . and .. come from? Where could they be seen as a way of navigating a file system tree for the first time? Excerpt from an interview with Ken Thompson (9-6-89): Every time we made a directory, by convention we put it in another directory called directory - directory, which was dd. Its name was dd and that all the users directories and in fact most other directories, users maintain their own directory systems, had pointers back to dd, and dd got shortened into ‘dot-dot,’ and dd was for directory-directory. I

At times I want to revisit a change I committed to SVN a short while back, but don't recall the specific files involved or the revision number. So I would like to see a list of recent commit messages, ideally including the files included in each commit. I picture going to the root of my working copy and entering something like the following to see the messages and files associated with the most recent 5 commits: svn log -l5 -v * Unfortunately, this command requires a single target, and won't accept '*'. I know SVN has the information I want. Is there a simple way to retrieve it? You can use

I understand it's off topic, I couldn't find anywhere online and I was thinking maybe programming gurus in the community might know this. I usually use kill -9 pid to kill the job. I always wondered the origin of 9. I looked it up online, and it says "9 Means KILL signal that is not catchable or ignorable. In other words it would signal process (some running application) to quit immediately" (source: http://wiki.answers.com/Q/What_does_kill_-9_do_in_unix_in_its_entirety ) But, why 9? and what about the other numbers? is there any historical significance or because of the architecture of Unix?