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Providing less than operator for one element of a pair


Providing less than operator for one element of a pair

By : Saber Abushiba
Date : October 23 2020, 11:12 PM
Any of those help When you are implementing a comparator that implements some specific and/or fairly exotic comparison approach, it is better to use a named function or a function object instead of hijacking the operator < for that purpose. I'd say that the natural way to compare a std::pair object would be to use lexicographical comparison. Since your comparison is not lexicographical, taking over operator < might not be a good idea. Better implement a comparator class
code :


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`pair::operator=(pair&&)` error with `auto&` deduced move operations - libstdc++ regression?

`pair::operator=(pair&&)` error with `auto&` deduced move operations - libstdc++ regression?


By : Christopher
Date : March 29 2020, 07:55 AM
will be helpful for those in need This is almost certainly a point-of-instantiation issue. If you do something that triggers the instantiation of pair's definition in main, then you get the error. Otherwise, it's only instantiated when vector::emplace is instantiated, which the implementations at issue here defer to the end of the translation unit (which is allowed, see [temp.point]/8), at which point the assignment operator is fully defined and callable.
a(v) triggers the instantiation of the definition of pair because it's needed for ADL. If you write ::a(v) or (a)(v) (both suppress ADL) then the error disappears. (Obviously, a.back().first requires the instantiation of pair: you are accessing its data member.)
Function with 'varargin' giving error when providing name-value pair only: MATLAB

Function with 'varargin' giving error when providing name-value pair only: MATLAB


By : Alex Franklin
Date : March 29 2020, 07:55 AM
around this issue You're right that the parser appears to give some odd results, a related question might be this one.
One work-around, which works for your function in its current form, would be to add a check for if 2 inputs are given. If there are 2 inputs, assume it's your OnlyDirectories flag and use the default name value. The code would look like this and passes all 4 of your example use cases.
code :
function list = dir2(varargin)
    p = inputParser;
    addOptional(p, 'name', '.', @ischar);
    addParameter(p, 'OnlyDirectories', false, @islogical);
    if numel(varargin) == 2 
        varargin = [{'.'}, varargin]; 
    end
    parse(p, varargin{:});
    list = dir(p.Results.name);
    if p.Results.OnlyDirectories
        dirFlags = [list.isdir];
        list = list(dirFlags); 
    end
    list = list(arrayfun(@(x) ~strcmp(x.name(1),'.'), list)); 
end
function list = dir2(varargin)
    p = inputParser;
    addParameter(p, 'name', '.', @ischar);
    addParameter(p, 'OnlyDirectories', false, @islogical);
    % ... other code
end
construct key value pair array by providing list of values(string)

construct key value pair array by providing list of values(string)


By : Shaun Santa Cruz
Date : March 29 2020, 07:55 AM
I wish this helpful for you You want to split the string on the comma then convert each string you receive in to an object
code :
var placeList = tag.split(',').map(str => ({place: str}))
Is there any drawbacks in providing operator+ or operator- to bidirectional iterators?

Is there any drawbacks in providing operator+ or operator- to bidirectional iterators?


By : user3549990
Date : March 29 2020, 07:55 AM
hop of those help? The bidirectional iterators have no luxuries like random access iterators, and hence need to depend upon the std::next and std::prev, when someone needs to do operations like ,
If not, isn't nice to have in the C++ standard library?
Error: no match for 'operator[]' (operand types are 'std::list<std::pair<int, int> >*' and 'std::pair<int

Error: no match for 'operator[]' (operand types are 'std::list<std::pair<int, int> >*' and 'std::pair<int


By : Padmore Yeboah
Date : March 29 2020, 07:55 AM
wish helps you adj is of type std::list>*, which is a pointer. Pointers implement the following operator[]
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