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Easiest way to check for an index or a key in an array?
... associative array)
[ ${array[key]+abc} ] && echo "exists"
Basically what ${array[key]+abc} does is
if array[key] is set, return abc
if array[key] is not set, return nothing
References:
See Parameter Expansion in Bash manual and the little note
if the colon is omitted, the ope...
How to compare if two structs, slices or maps are equal?
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@GeneralLeeSpeaking that's not true. From the cmp documentation: "Pointers are equal if the underlying values they point to are also equal"
– Ilia Choly
Dec 29 '18 at 18:11
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What is JSON and why would I use it?
...the official documentation, but I still haven't got to the point where I really understand what JSON is, and why I'd use it.
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Retrieving the last record in each group - MySQL
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MySQL 8.0 now supports windowing functions, like almost all popular SQL implementations. With this standard syntax, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m...
What are the -Xms and -Xmx parameters when starting JVM?
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The flag Xmx specifies the maximum memory allocation pool for a Java virtual machine (JVM), while Xms specifies the initial memory allocation pool.
This means that your JVM will be started with Xms amount of memory and will be able to use a maximum of Xmx amount of ...
What does Provider in JAX-RS mean?
...tomizing the JAX-RS runtime. You can think of them as plugins that (potentially) alter the behavior of the runtime, in order to accomplish a set of (program defined) goals.
Providers are not the same as resources classes, they exist, conceptually, at a level in-between resources classes and the JAX...
Typedef function pointer?
I'm learning how to dynamically load DLL's but what I don't understand is this line
6 Answers
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How can I get the current language in Django?
...t: Returns None if translations are temporarily deactivated (by deactivate_all() or when None is passed to override()). Before Django 1.8, get_language() always returned LANGUAGE_CODE when translations were deactivated.
– Pieter
Jan 3 '17 at 13:11
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Using reflect, how do you set the value of a struct field?
...rue if the value's
address can be obtained with Addr.
Such values are called addressable. A
value is addressable if it is an
element of a slice, an element of an
addressable array, a field of an
addressable struct, or the result of
dereferencing a pointer. If CanAddr
returns false, c...
How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version
I am trying to use Notepad++ as my all-in-one tool edit, run, compile, etc.
51 Answers
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