A library for C++20 that introduced std::ranges namespace, which consists of rangified algorithms from
Questions tagged [std-ranges]
379 questions
1
vote
3 answers
C++20: Why can't range adaptors and ranges be combined in one expression?
I am looking at the following snippet:
std::vector elements{ 1,2,3 };
// this won't compile:
elements
| std::views::filter([](auto i) { return i % 2 == 0; })
| std::ranges::for_each([](auto e) {std::cout << e << std::endl; });
// but…
Angle.Bracket
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1 answer
Read file and split and trim each line with cpp20
I have created a code that fits my specific need - to split the string (read from a file) at comma stripping any whitespaces. also, I want to convert these substrings to double and store them in std::vector.
I use ranges library in c++20 and…
AmirSalar
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1
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1 answer
Standard algorithm to operate on adjacent elements
std::adjacent_find looks for the first two consecutive elements that satisfies the given predicate. I am looking for other algorithms that also has a predicate that takes the (previous, current) pair. This is useful for rendering polygons, computing…
user877329
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1 answer
Error with C++20 ranges and std::views::take
I was experimenting with C++20 ranges and I got the following strange behavior when compiling with GCC 11.1.0 and CMake 3.20.3. Specifically, the following code doesn't compile:
auto Foo() {
std::vector x{1, 2, 3, 4, 5, 6};
return…
fdev
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- 12
1
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1 answer
C++20: Concept function, restricted with an archtype takes wider range of inputs, than desired
Given concept test which has a function that takes an input range.
template
concept test = requires(T t, archtypes::Input_Range t_range)
{
{ t.count(t_range) } -> std::same_as;
};
This archtype allows for the count function to…
freeman23
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1
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2 answers
What is the point of c++20 ranges?
I struggle to understand what c++20 ranges add compared to good old fashioned iterators. Yes, I guess there is no need to use begin and end anymore, but simple overloads such as:
namespace std {
template
auto…
SomeProgrammer
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4 answers
Is it possible to create a view of references from objects?
To illustrate what I mean: I have three objects:
Foo first, even, odd;
And I want to construct a view consisting of references to these objects like this: first&, odd&, even&, odd& ... up to N. To be able to iterate over them:
for (const auto &…
cos
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1 answer
Why can't I construct a string_view from range iterators?
C++20 adds a constructor for basic_string_view which takes two iterators. However, when I try to construct a string_view with the iterators from a common range I get an error.
#include
#include
using namespace std::views;
int…
Chris_F
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error: no match for call to '(const std::ranges::__sort_fn)
I was practicing vectors and ranges in c++ 20 was stuck at following state.
#include
#include
#include
#include
#include
namespace ranges = std::ranges;
struct Model
{
double…
Inyoung Kim 김인영
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0 answers
How can I rotate a particular subset of a vector?
I want to rotate a subset of an vector inside the whole vector. The subset to be rotated is defined by another vector.
What I want to achieve is this:
template
void rotateSubset(CONTAINER& whole, const CONTAINER& subset)
{
//…
Liam Goodacre
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1
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3 answers
Can / should I use the ranges library to emulate set functions?
I want to apply a view::filter to a vector in order to find the set_intersection (or set_difference, etc) of it with another vector.
My interest in doing this is that it would allow you to alter a particular subset of the original container (and…
Liam Goodacre
- 381
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- 10
1
vote
3 answers
C++ std:: string starts_with/ends_with case insensitive versions?
C++20 added starts_with, ends_with to std::string.
Is there a nice way to get it to be case insensitive?
Note that perf matters so I do not want to lowercase/uppercase both strings(or std::min(len1, len2) parts of them).
Unlike regular …
NoSenseEtAl
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2 answers
Is the code for sorting a std::vector by length correct in C++20?
I wrote a code that sorts vector strings by length. Unfortunately, I'm not sure whether it will work in the next standard in this form. Is this the correct code in C++20?
#include
#include
#include
#include …
Dessus
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0 answers
Added and removed elements between two data structures of type std::unordered_map>
What's the most efficient way to retrieve the added and removed elements between two structure of type:
using T = unordered_map>;
I wrote this code.
Could you please advise?
#include
#include…
Peter
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0
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what is faster, std::sort then set_intersection, or std::unordered_map with double for-loop find?
what is a faster?
sort two vectors and then do set_intersection... or
auto intersection = std::make_shared();
std::sort(m_currentSearchResults->begin(), m_currentSearchResults->end());
std::sort(graphSearchResultMediaItems->begin(),…
chrisg
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