56
votes
14
answers
1.3K
views
How do I pass environment variables to Docker containers?
I'm new to Docker, and it's unclear how to access an external database from a container. Is the best
47
votes
8
answers
1.3K
views
MySQL: Large VARCHAR vs. TEXT?
I've got a messages table in MySQL which records messages between users. Apart from the typical ids and m
51
votes
5
answers
2.4K
views
How do I delete an exported environment variable?
Before installing gnuplot, I set the environment variable GNUPLOT_DRIVER_DIR = /home/gnuplot/build/src. During
50
votes
2
answers
739
views
In MATLAB, are variables REALLY double-precision by default?
This question arose out of something strange that I noticed after investigating this question further... I al
56
votes
9
answers
1.9K
views
Using i and j as variables in MATLAB
i and j are very popular variable names (see e.g., this question and this one). For example, in loops: for i=1
56
votes
6
answers
3.1K
views
How to get the type of a variable in MATLAB
Does MATLAB have a function/operator that indicates the type of a variable (similar to the typeof operator in
68
votes
9
answers
459
views
How can I index a MATLAB array returned by a function without first assigning it to a local variable?
For example, if I want to read the middle value from magic(5), I can do so like this: M = magic(5); value = M
58
votes
30
answers
2.5K
views
How to check if a variable is set in Bash?
How do I know if a variable is set in Bash? For example, how do I check if the user gave the first parameter
46
votes
14
answers
858
views
How to set ASPNETCORE_ENVIRONMENT to be considered for publishing an ASP.NET Core application
When I publish my ASP.NET Core web application to my local file system, it always takes the production-config
71
votes
9
answers
2K
views
Static vs class functions/variables in Swift classes?
The following code compiles in Swift 1.2: class myClass { static func myMethod1() { } class func
51
votes
7
answers
1.8K
views
Read environment variables in Node.js
Is there a way to read environment variables in Node.js code? Like for example Python's os.environ[&apos
52
votes
15
answers
3.1K
views
How to access environment variable values
I set an environment variable that I want to access in my Python application. How do I get its value?
55
votes
23
answers
870
views
What does ** (double star/asterisk) and * (star/asterisk) do for parameters?
In the following method definitions, what does the * and ** do for param2? def foo(param1, *param2): def bar(
65
votes
21
answers
459
views
Using global variables in a function
How can I create or use a global variable in a function? If I create a global variable in one function, how c
64
votes
11
answers
981
views
Why don't Java's +=, -=, *=, /= compound assignment operators require casting?
Until today, I thought that for example: i += j; Was just a shortcut for: i = i + j; But if we try this:
58
votes
30
answers
1K
views
How can I determine if a variable is 'undefined' or 'null'?
How do I determine if variable is undefined or null? My code is as follows: var EmpName = $("div#esd-names d
57
votes
30
answers
1K
views
What's the difference between using "let" and "var"?
ECMAScript 6 introduced the let statement. I've heard that it's described as a local variable, but I
62
votes
30
answers
1.9K
views
58
votes
29
answers
571
views
"Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset" using PHP
I'm running a PHP script and continue to receive errors like: Notice: Undefined variable: my_variable_na
56
votes
28
answers
1.8K
views
How to get the client IP address in PHP
How can I get the client IP address using PHP? I want to keep record of the user who logged into my website t
