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Resolving ambiguous overload on function pointer and std::function for a lambda using + (unary plus)
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A positive lambda: '+[]{}' - What sorcery is this? [duplicate]
(1 answer)
Closed 2 years ago.
int main()
{
void(*fp1)() = []{}; // ok
void(*fp2)() = +[]{}; // also ok
}
I cannot find any explanation in cppreference.com on the meaning of sign + in front of the lambda.
What is the exact meaning of sign + here as per the C++ standard?
Related
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Why cast unused return values to void?
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I was working and suddenly I faced a function like that:
void func(SomeStruct *parameter) { (void)parameter; }
I could not wrap my head on what it does.
I mean, there is a function func which the only thing it does is (void)parameter; but I can't get what (void)parameter; is doing int this example.
Would someone mind to explain me, please?
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Hi I came across this example
auto [ptr, ec] { std::from_chars(str.data(), str.data() + str.size(), result) };
Can someone please explain the what is the syntax autp [ptr,ec] {} , this is something I am seeing for the first time. Is this new in C++ ?
Any link to the documentation will be very much appreciated.
Thanks
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I'm going through Wt web framework tutorial, in one example they initialize a variable this way:
auto greet = [this]{
greeting_->setText("Hello there, " + nameEdit_->text());
};
What does square brackets mean in this type of initialization?
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I read a piece of code from a book but I do not really understand the grammar,
const auto& [local_min, local_max] = minmax(A[i], A[i+1]);
where A is vector of int and local_min and local_max are int.
I know minmax returns a pair, but what does the square brackets do, i.e. [local_min, local_max]? I guess it is not for arrays here.
Thanks.
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What is the point of the 'auto' keyword?
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C++ auto keyword. Why is it magic?
(8 answers)
Closed 9 years ago.
I recently came accross the keyword auto in c++.
In the code:
auto maxIterator = std::max_element(&spec[0], &spec[sampleSize]);
float maxVol = *maxIterator;
// Normalize
if (maxVol != 0)
std::transform(&spec[0], &spec[sampleSize], &spec[0], [maxVol] (float dB) -> float { return dB / maxVol; });
This is to do with running a frequency analysis on a audio stream.
From the website: http://katyscode.wordpress.com/2013/01/16/cutting-your-teeth-on-fmod-part-4-frequency-analysis-graphic-equalizer-beat-detection-and-bpm-estimation/
I have searched the forums but It says that there is no use for the keyword. Could someone please explain the use of it here.
I am quite new to c++ so please try not to make the answers too complicated.
Thanks so much all.
Did auto make maxIterator a pointer also?
Compiler guess maxIterator's type. If spec's type is float [], maxIterator type is float *.
In C++11, the keyword auto deduces the type of declared variable from its initialization expression. Hence, in your code it deduces type of maxIterator.
For more information on auto look here