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What is the difference between syntax and semantics in programming languages?
...he language. It answers the question: how do I construct a valid sentence? All languages, even English and other human (aka "natural") languages have grammars, that is, rules that define whether or not the sentence is properly constructed.
Here are some C language syntax rules:
separate statement...
How to efficiently build a tree from a flat structure?
... objects in a hash table mapping to the specific object. Enumerate through all the objects and find their parent if it exists and update its parent pointer accordingly.
class MyObject
{ // The actual object
public int ParentID { get; set; }
public int ID { get; set; }
}
class Node
{
pu...
Passing parameters to addTarget:action:forControlEvents
...wsDetails: method here. You just create a selector to make button able to call it when certain action occurs (touch up in your case). Controls can use 3 types of selectors to respond to actions, all of them have predefined meaning of their parameters:
with no parameters
action:@selector(switchToN...
How to count duplicate value in an array in javascript
...- it was me; I was browsing on mobile, and have clicked the button w/o actually noticing. Once I found out it was too late to revert. Apologies for that, the answer is really good. If you want to edit it, I'd be glad to reverse.
– Todor Minakov
Jan 19 '19 at 10...
Why call git branch --unset-upstream to fixup?
.... Once local branch L is set to track remote-tracking branch R, Git will call R its "upstream" and tell you whether you're "ahead" and/or "behind" the upstream (in terms of commits). It's normal (even recommend-able) for the local branch and remote-tracking branches to use the same name (except fo...
Convert Long into Integer
...yslov the question was about Long values, not about null values. And personally I believe in rejecting null up front rather than using null in -> null out and thereby transporting null through my application. So one could also argue this is the worst answer :-)
– Sean Patric...
Get the position of a div/span tag
...n will tell you the x,y position of the element relative to the page. Basically you have to loop up through all the element's parents and add their offsets together.
function getPos(el) {
// yay readability
for (var lx=0, ly=0;
el != null;
lx += el.offsetLeft, ly += el.off...
How to get different colored lines for different plots in a single figure?
...have to identify each plot with a different color which should be automatically generated by Python.
5 Answers
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How do I pass a unique_ptr argument to a constructor or a function?
...e_ptr<Base> n)
: next(std::move(n)) {}
In order for the user to call this, they must do one of the following:
Base newBase(std::move(nextBase));
Base fromTemp(std::unique_ptr<Base>(new Base(...));
To take a unique pointer by value means that you are transferring ownership of the p...
How to query MongoDB with “like”?
...
Actually, it depends. If the query doesn't use an index, and must do a table scan, then it can certainly be expensive. If you're doing a 'starts with' regex query, then that can use an index. Best to run an explain() to see what'...