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Best way to test if a row exists in a MySQL table
...RE ...)
and per the documentation, you can SELECT anything.
Traditionally, an EXISTS subquery starts with SELECT *, but it could
begin with SELECT 5 or SELECT column1 or anything at all. MySQL
ignores the SELECT list in such a subquery, so it makes no difference.
...
Is there a function to make a copy of a PHP array to another?
...ewLarsson raises a point in the comments below. PHP has a special feature called "references". They are somewhat similar to pointers in languages like C/C++, but not quite the same. If your array contains references, then while the array itself is passed by copy, the references will still resolve to...
How to remove gaps between subplots in matplotlib?
...s the subplots from stretching to an arbitrary aspect ratio and filling up all the empty space.
Normally, this would work:
import matplotlib.pyplot as plt
ax = [plt.subplot(2,2,i+1) for i in range(4)]
for a in ax:
a.set_xticklabels([])
a.set_yticklabels([])
plt.subplots_adjust(wspace=0,...
Verifying that a string contains only letters in C#
...
This assumes a latin alphabet, where Char.IsLetter allows for non-latin alphabets.
– Paul van Brenk
Jul 28 '09 at 7:31
5
...
搭建高可用mongodb集群（二）—— 副本集 - 大数据 & AI - 清泛网 - 专注C/...
...(config);
#输出成功
{
"info" : "Config now saved locally. Should come online in about a minute.",
"ok" : 1
}
#查看日志，副本集启动成功后，138为主节点PRIMARY，136、137为副本节点SECONDARY。
Sun Dec 29 20:26:13.842 [conn3] replSet repl...
How does collections.defaultdict work?
...
Usually, a Python dictionary throws a KeyError if you try to get an item with a key that is not currently in the dictionary. The defaultdict in contrast will simply create any items that you try to access (provided of course th...
What is the JavaScript equivalent of var_dump or print_r in PHP? [duplicate]
...
This really is not a proper answer as this is not an inherent feature or function of JavaScript and there are innumerable scenarios where one will absolutely not have access to console.log()
– Chris Rasys
...
Auto-loading lib files in Rails 4
.../foo.rb:
class Foo
end
in lib/foo/bar.rb:
class Foo::Bar
end
if you really wanna do some monkey patches in file like lib/extensions.rb, you may manually require it:
in config/initializers/require.rb:
require "#{Rails.root}/lib/extensions"
P.S.
Rails 3 Autoload Modules/Classes by Bill H...
How to debug heap corruption errors?
...nctionality was in Application Verifier.
Electric Fence (aka "efence"), dmalloc, valgrind, and so forth are all worth mentioning, but most of these are much easier to get running under *nix than Windows. Valgrind is ridiculously flexible: I've debugged large server software with many heap issues u...
Why does this code segfault on 64-bit architecture but work fine on 32-bit?
...o int* masks the fact that without the proper #include the return type of malloc is assumed to be int. IA-64 happens to have sizeof(int) < sizeof(int*) which makes this problem obvious.
(Note also that because of the undefined behaviour it could still fail even on a platform where sizeof(int)==...