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How does PHP 'foreach' actually work?
Let me prefix this by saying that I know what foreach is, does and how to use it. This question concerns how it works under the bonnet, and I don't want any answers along the lines of "this is how you loop an array with foreach ".
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O(nlogn) Algorithm - Find three evenly spaced ones within binary string
I had this question on an Algorithms test yesterday, and I can't figure out the answer. It is driving me absolutely crazy, because it was worth about 40 points. I figure that most of the class didn't solve it correctly, because I haven't come up with a solution in the past 24 hours.
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Accessing inactive union member and undefined behavior?
...the impression that accessing a union member other than the last one set is UB, but I can't seem to find a solid reference (other than answers claiming it's UB but without any support from the standard).
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How does “this” keyword work within a function?
...veral objects using object-literal notation. Inside those objects, the this pointer is being used. From the behavior of the program, I have deduced that the this pointer is referring to the class on which the method was invoked, and not the object being created by the literal.
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Difference between abstraction and encapsulation?
What is the precise difference between encapsulation and abstraction?
39 Answers
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Not equal != operator on NULL
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<> is Standard SQL-92; != is its equivalent. Both evaluate for values, which NULL is not -- NULL is a placeholder to say there is the absence of a value.
Which is why you can only use IS NULL/IS NOT NULL as predicates for such...
When is JavaScript synchronous?
... asynchronous. However, I have learned that there are situations where it is not (ie DOM manipulations). Is there a good reference anywhere about when it will be synchronous and when it will be asynchronous? Does jQuery affect this at all?
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How do SO_REUSEADDR and SO_REUSEPORT differ?
... Some operating systems don't even have the option SO_REUSEPORT . The WEB is full of contradicting information regarding this subject and often you can find information that is only true for one socket implementation of a specific operating system, which may not even be explicitly mentioned in the ...
Is C++ context-free or context-sensitive?
I often hear claims that C++ is a context-sensitive language. Take the following example:
20 Answers
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Regular vs Context Free Grammars
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Regular grammar is either right or left linear, whereas context free grammar is basically any combination of terminals and non-terminals. Hence you can see that regular grammar is a subset of context-free grammar.
So for a palindrome for in...