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What is the difference between PS1 and PROMPT_COMMAND
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From the GNU Bash doc page: http://www.gnu.org/software/bash/manual/bashref.html
PROMPT_COMMAND
If set, the value is interpreted as a command to execute before
the printing of each primary prompt ($PS1).
I never used it, but I could have used this back when...
How to convert java.util.Date to java.sql.Date?
...classes instead of legacy java.util.Date & java.sql.Date with JDBC 4.2 or later.
Convert to/from java.time if inter-operating with code not yet updated to java.time.
Example query with PreparedStatement.
myPreparedStatement.setObject(
… , // Specif...
Arrow operator (->) usage in C
...ace). I was reading the chapter on pointers and the -> (arrow) operator came up without explanation. I think that it is used to call members and functions (like the equivalent of the . (dot) operator, but for pointers instead of members). But I am not entirely sure.
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How to set std::tuple element by index?
...onst version of get returns a reference. You can assign to the reference. For example, suppose t is tuple, then: get<0>(t) = 3;
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How to center a button within a div?
...ing because I noticed it's an active answer, however Flexbox would be the correct approach now.
Live Demo
Vertical and horizontal alignment.
#wrapper {
display: flex;
align-items: center;
justify-content: center;
}
Just horizontal (as long as the main flex axis is horizontal which is defa...
When would you use the different git merge strategies?
...h resolve, but I've used the others:
Recursive
Recursive is the default for non-fast-forward merges. We're all familiar with that one.
Octopus
I've used octopus when I've had several trees that needed to be merged. You see this in larger projects where many branches have had independent develop...
How to do a safe join pathname in ruby?
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One thing to note. Ruby uses a "/" for file separator on all platforms, including Windows, so you don't actually need use different code for joining things together on different platforms. "C:/tmp/1.text" should work fine.
File.join() is your friend for joinin...
Remove characters except digits from string using Python?
...translate method:
>>> x='aaa12333bb445bb54b5b52'
>>> import string
>>> all=string.maketrans('','')
>>> nodigs=all.translate(all, string.digits)
>>> x.translate(all, nodigs)
'1233344554552'
>>>
string.maketrans makes a translation table (a str...
In which order do CSS stylesheets override?
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The rules for CSS rule cascading are complex -- rather than trying to paraphrase them badly, I'll simply refer you to the spec:
http://www.w3.org/TR/2011/REC-CSS2-20110607/cascade.html#cascade
In short: more specific rules override mo...
When is std::weak_ptr useful?
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A good example would be a cache.
For recently accessed objects, you want to keep them in memory, so you hold a strong pointer to them. Periodically, you scan the cache and decide which objects have not been accessed recently. You don't need to keep those in m...