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How does facebook, gmail send the real time notification?
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The way Facebook does this is pretty interesting.
A common method of doing such notifications is to poll a script on the server (using AJAX) on a given interval (perhaps every few seconds), to check if something has happened. However, this ...
What does $_ mean in PowerShell?
I've seen the following a lot in PowerShell, but what does it do exactly?
6 Answers
6
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Why does this iterative list-growing code give IndexError: list assignment index out of range?
...ut you're attempting to write to element [0] in the first iteration, which doesn't exist yet.
Try the following instead, to add a new element to the end of the list:
for l in i:
j.append(l)
Of course, you'd never do this in practice if all you wanted to do was to copy an existing list. You'd...
What does the CSS rule “clear: both” do?
What does the following CSS rule do:
5 Answers
5
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Does JavaScript have a built in stringbuilder class?
...ipt introduced string literals.
var classType = "stringbuilder";
var q = `Does JavaScript have a built-in ${classType} class?`;
Notice that back-ticks, instead of single quotes, enclose the string.
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What does the “-U” option stand for in pip install -U
...ling, I can't find any docs for pip's command line options/arguments. What does pip install -U mean? Does anyone have a link to a list of pip's options and arguments?
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TypeError: 'str' does not support the buffer interface
...riginal code worked for me under 3.1, and the sample code in the docs also does not encode explicitly. If you use it on non-ASCII text, does gunzip decompress it? I got an error.
– Tom Zych
Mar 29 '11 at 10:59
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How to check if mysql database exists
...ts is:
SHOW DATABASES LIKE 'dbname';
If database with the name 'dbname' doesn't exist, you get an empty set. If it does exist, you get one row.
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What is std::promise?
... of several promises and associated futures and have a single thread which does several calculations and sets a result on each promise. async would only allow you to return a single result, to return several you would need to call async several times, which might waste resources.
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Why does “while(true)” without “Thread.sleep” cause 100% CPU usage on Linux but not on Windows?
..., top on Linux runs in so-called IRIX mode, while the Windows Task Manager does not. Let's say you have 4 cores:
With IRIX mode on, 1 fully utilized core is 100% and 4 cores are 400%.
With IRIX mode off, 1 fully utilized core is 25% and 4 cores are 100%.
This means that by default, top on Linu...