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JavaScript checking for null vs. undefined and difference between == and ===
...hey're falsey:
if (!a) {
// `a` is falsey, which includes `undefined` and `null`
// (and `""`, and `0`, and `NaN`, and [of course] `false`)
}
This is defined by ToBoolean in the spec.
...and what is the difference between the null and undefined?
They're both values usually used to i...
Real life example, when to use OUTER / CROSS APPLY in SQL
I have been looking at CROSS / OUTER APPLY with a colleague and we're struggling to find real life examples of where to use them.
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ROW_NUMBER() in MySQL
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SELECT t0.col3
FROM table AS t0
LEFT JOIN table AS t1 ON t0.col1=t1.col1 AND t0.col2=t1.col2 AND t1.col3>t0.col3
WHERE t1.col1 IS NULL;
“Get the rows in the table for which no other row with matching col1,col2 has a higher col3.” (You will notice this and most other groupwise-maximum solu...
How do I declare and initialize an array in Java?
How do I declare and initialize an array in Java?
28 Answers
28
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Peak detection in a 2D array
...nic measuring pressure under a dogs paw. I use Python for my data analysis and now I'm stuck trying to divide the paws into (anatomical) subregions.
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Unicode equivalents for \w and \b in Java regular expressions?
Many modern regex implementations interpret the \w character class shorthand as "any letter, digit, or connecting punctuation" (usually: underscore). That way, a regex like \w+ matches words like hello , élève , GOÄ_432 or gefräßig .
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Cutting the videos based on start and end time using ffmpeg
I tried to cut the video using the start and end time of the video by using the following command
9 Answers
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How can I match a string with a regex in Bash?
...is not a concern, I recommend using [[ instead of [ or test as it is safer and more powerful. See What is the difference between test, [ and [[ ? for details.
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Comparing numbers in Bash
...hen
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fi
For POSIX shells that don't support (()), you can use -lt and -gt.
if [ "$a" -gt "$b" ]; then
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fi
You can get a full list of comparison operators with help test or man test.
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Git for beginners: The definitive practical guide
...k, after seeing this post by PJ Hyett , I have decided to skip to the end and go with Git .
37 Answers
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