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How to use NULL or empty string in SQL
...pty string. REASON: if there is ONLY whitespace, a single trim will remove all of it. For example, you don't care whether the comparison fails because what remains is "abc" or " abc".
– ToolmakerSteve
Dec 9 '16 at 20:06
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Calling closure assigned to object property directly
...sn't work on a StdClass.
Before PHP7, you'd have to implement the magic __call method to intercept the call and invoke the callback (which is not possible for StdClass of course, because you cannot add the __call method)
class Foo
{
public function __call($method, $args)
{
if(is_...
Regex to replace multiple spaces with a single space
...place \s\s+ with ' ':
string = string.replace(/\s\s+/g, ' ');
If you really want to cover only spaces (and thus not tabs, newlines, etc), do so:
string = string.replace(/ +/g, ' ');
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returning a Void object
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then what is the generically correct way to achieve a return type of void?
– Robert
Mar 9 '10 at 11:40
1
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Passing arrays as url parameter
...5D=4&aParam%5Ba%5D=b&aParam%5Bc%5D=d"
http_build_query() handles all the necessary escaping for you (%5B => [ and %5D => ]), so this string is equal to aParam[0]=1&aParam[1]=4&aParam[a]=b&aParam[c]=d.
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How to print a list of symbols exported from a dynamic library
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Use nm -a your.dylib
It will print all the symbols including globals
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Difference between Covariance & Contra-variance
...ng function that associates one member of a set with another. More specifically, a mapping can be covariant or contravariant with respect to a relation on that set.
Consider the following two subsets of the set of all C# types. First:
{ Animal,
Tiger,
Fruit,
Banana }.
And second, this c...
What is difference between instantiating an object using new vs. without
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The line:
Time t (12, 0, 0);
... allocates a variable of type Time in local scope, generally on the stack, which will be destroyed when its scope ends.
By contrast:
Time* t = new Time(12, 0, 0);
... allocates a block of memory by calling either ::operato...
Best way to determine user's locale within browser
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Unfortunately this header is not available for reading inside JavaScript; all you get is navigator.language, which tells you what localised version of the web browser was installed. This is not necessarily the same thing as the user's preferred language(s). On IE you instead get systemLanguage (OS ...
Split code over multiple lines in an R script
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Bah, comments are too small. Anyway, @Dirk is very right.
R doesn't need to be told the code starts at the next line. It is smarter than Python ;-) and will just continue to read the next line whenever it considers the statement as "not finished". ...