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What is 'Pattern Matching' in functional languages?
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edited May 23 '17 at 12:10
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answered Mar 23 '10 at 18:58
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Accessing nested JavaScript objects and arays by string path
... // strip a leading dot
var a = s.split('.');
for (var i = 0, n = a.length; i < n; ++i) {
var k = a[i];
if (k in o) {
o = o[k];
} else {
return;
}
}
return o;
}
Usage::
Object.byString(someObj, 'part3[0].name');
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What is “:-!!” in C code?
... in effect, a way to check whether the expression e can be evaluated to be 0, and if not, to fail the build.
The macro is somewhat misnamed; it should be something more like BUILD_BUG_OR_ZERO, rather than ...ON_ZERO. (There have been occasional discussions about whether this is a confusing name.)
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COUNT DISTINCT with CONDITIONS
...count(distinct tag) as tag_count,
count(distinct (case when entryId > 0 then tag end)) as positive_tag_count
from
your_table_name;
The first count(distinct...) is easy.
The second one, looks somewhat complex, is actually the same as the first one, except that you use case...when clause. In ...
C# short/long/int literal format?
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var d = 1.0d; // double
var d0 = 1.0; // double
var d1 = 1e+3; // double
var d2 = 1e-3; // double
var f = 1.0f; // float
var m = 1.0m; // decimal
var i = 1; // int
var ui = 1U; // uint
var ul = 1UL; // ulong
var l =...
How to count total lines changed by a specific author in a Git repository?
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320
The output of the following command should be reasonably easy to send to script to add up the to...
An “and” operator for an “if” statement in Bash
...US} is empty. It would probably be better to do:
if ! [ "${STATUS}" -eq 200 ] 2> /dev/null && [ "${STRING}" != "${VALUE}" ]; then
or
if [ "${STATUS}" != 200 ] && [ "${STRING}" != "${VALUE}" ]; then
It's hard to say, since you haven't shown us exactly what is going wrong wit...
How do I parse JSON with Objective-C?
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With the perspective of the OS X v10.7 and iOS 5 launches, probably the first thing to recommend now is NSJSONSerialization, Apple's supplied JSON parser. Use third-party options only as a fallback if you find that class unavailable at runtime.
So, for exampl...
Is SQL or even TSQL Turing Complete?
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Qantas 94 Heavy
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answered Sep 28 '11 at 7:59
Jan de VosJan de Vos
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?: operator (the 'Elvis operator') in PHP
...will leave foo unchanged.
Some more examples:
<?php
var_dump(5 ?: 0); // 5
var_dump(false ?: 0); // 0
var_dump(null ?: 'foo'); // 'foo'
var_dump(true ?: 123); // true
var_dump('rock' ?: 'roll'); // 'rock'
?>
By the way, it's called the Elvis operator.
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