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Meaning of $? (dollar question mark) in shell scripts

... This is the exit status of the last executed command. For example the command true always returns a status of 0 and false always returns a status of 1: true echo $? # echoes 0 false echo $? # echoes 1 From the manual: (acessible by calling man bash in your shell) $?...
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Why in Java 8 split sometimes removes empty strings at start of result array?

...ehavior of String.split (which calls Pattern.split) changes between Java 7 and Java 8. Documentation Comparing between the documentation of Pattern.split in Java 7 and Java 8, we observe the following clause being added: When there is a positive-width match at the beginning of the input sequen...
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How to declare a variable in MySQL?

... refer to a variable that has not been initialized, it has a value of NULL and a type of string. SELECT @var_any_var_name You can initialize a variable using SET or SELECT statement: SET @start = 1, @finish = 10; or SELECT @start := 1, @finish := 10; SELECT * FROM places WHERE place BET...
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Downcasting in Java

... @UnKnown: it shouldn't. Double check that you actually compiled and ran that version and if you can still reproduce it, post a separate question (with an SSCCE). – Joachim Sauer Apr 20 '16 at 16:04 ...
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Most efficient T-SQL way to pad a varchar on the left to a certain length?

...right('XXXXXXXXXXXX'+ rtrim(@str), @n) where X is your padding character and @n is the number of characters in the resulting string (assuming you need the padding because you are dealing with a fixed length). But as I said you should really avoid doing this in your database. ...
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Exporting functions from a DLL with dllexport

...e is an option "Compile As" which corresponds to the compiler switches /TP and /TC. If you still want to use C++ to write the internals of your lib but export some functions unmangled for use outside C++, see the second section below. Exporting/Importing DLL Libs in VC++ What you really want to do i...
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Android notification is not showing

I need a program that will add a notification on Android. And when someone clicks on the notification, it should lead them to my second activity. ...
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Why does Twitter Bootstrap Use Pixels for Font Size?

...github.com/ivayloc/twbs-rem-em there is no need to make any calculation to convert pixels in rem or em units, there is build in @mixins for this - @include rem(property, values) - also fallback to px and for em convertion you can use em(value). ...
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printf format specifiers for uint32_t and size_t

...antic, then. It's probably going off the names of types in the source code and doesn't realize they're equivalent. I wonder what it would do with @KennyTM's answer... It certainly should be more portable. – Cogwheel Jul 2 '10 at 18:49 ...
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How do I measure time elapsed in Java? [duplicate]

...- starts; } public long time(TimeUnit unit) { return unit.convert(time(), TimeUnit.MILLISECONDS); } } Usage: TimeWatch watch = TimeWatch.start(); // do something long passedTimeInMs = watch.time(); long passedTimeInSeconds = watch.time(TimeUnit.SECONDS); Aft...