Use this tag for questions about the C++ standard library template std::tuple. It represents an ordered, heterogeneous sequence of objects. Also add the tag [c++] when using this tag.
Questions tagged [stdtuple]
403 questions
3
votes
1 answer
How to split a std::string_views into a tuple-like objects using C++20 std::views::split?
According to this problem, we can using C++20's std::views::split to split std::string_view into range of std::string_views:
std::string_view s = "this should be split into string_views";
auto views = s | std::views::split(' ')
|…
康桓瑋
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3
votes
1 answer
can I initialize an std::tuple from a vector array?
I have an std::vector containing a variant class. I want to construct a tuple with the same data. Is this possible? The normal construction methods for a tuple seem quite restrictive.
//In reality, I'm using JUCE::var.
…
Liam Goodacre
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3
votes
1 answer
Cleaner way of defining a constant vector of tuples in C++11
I have a constant vector of tuples, in which each tuple contains a key, name, quantity, value. This is how I am defining it-
// tuple of key, name, quantity, value
const std::vector >…
ravi
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3
votes
3 answers
how to forward the types of tuple to specialize other template?
currently I'm working on a dynamic container structure, which represents one pod value or has vector of pointers with same container type. The container has an interface optional expect_value() 。 For pod types the implemention is simple. For…
spiritsaway
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3
votes
2 answers
How to create a tuple of vectors of type deduced from a variadic template in C++17?
I have implemented a collection class that converts a vector of tuples to a tuple of vectors (it is essentially an AOS to SOA conversion). This code works for this example of two template classes. I was trying to make it more generic by using…
motam79
- 3,542
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3
votes
1 answer
Insert value to a std::map from a tuple
I am just learning data structure of graph.And i'm trapped in such a situation.
I have written my Graph class like
template
class Graph{};
where the Args of type char means the vertex of my Graph.
However, when i want to…
user9462517
3
votes
4 answers
Constructing tuple of value from tuple of reference, with one-argument templated constructor
I have a tuple of const references std::tuple from which I construct a tuple of values std::tuple. For any size of tuple greater than 1, this works fine: (online example: https://godbolt.org/g/24E8tU)
#include…
Lack
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3
votes
1 answer
Unpack std::tuple in-place without the artificial layer for std::index_sequence
I have a function template:
template
void set_args(const void* p, Us&... args);
I have a std::tuple that I want to unpack into args. My current solution is
template
void set_args_2(
const void*…
Lingxi
- 14,579
- 2
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- 93
3
votes
4 answers
Lambda function with map where key is tuple and value is double
I have a map, filled with values:
std::map, double> Cache;
When the size of map is greater than 100, I want to delete/erase only the map elements whose values in the key tuple are all more than 10. Here is how it can…
user8183713
3
votes
4 answers
Unclear syntax with std::tie
I'm just reading a bit about tuples.
Now the following syntax is not clear to me:
std::tie (myint, std::ignore, mychar) = mytuple;
It's not difficult to grasp what it does, BUT what happens from a language point of view? We are somehow assigning to…
Michael
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3
votes
1 answer
C++ perfect forward copy-only types to make_tuple
I'm playing with this little snippet:
#include
struct copy_only
{
copy_only() = default;
copy_only(copy_only&&) = delete;
copy_only(const copy_only&) = default;
};
template
void foo(Ts&& ...xs)
{
auto t =…
Przemek Kryger
- 687
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3
votes
2 answers
Issue with invalid use of incomplete type when using std::tuple_element
The following code implements a hash function for a std::tuple which is then used in a different segment of my code-base in a std::unordered_map of std::tuples.
// compute hash function recursively through each std::tuple element
template
sjrowlinson
- 3,297
- 1
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3
votes
1 answer
Forcing std::tuple to contain std::pair
Is it possible to use std::tuple "partly specialized" so that it contains std::pair with varying T?
UPD: the tuple should contain the pairs. So it is equivalent to using an array of fixed_t together with a regular std::tuple.
Alex
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3
votes
2 answers
How to compare tuples of different length?
I would like to write a comparator which compares tuples of different length but have the same "prefix". Consider following case, I have two tuples.
auto t1 = std::make_tuple(10, "Test1");
auto t2 = std::make_tuple(10, "Test", 3.14);
I would like…
kreuzerkrieg
- 3,009
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3
votes
1 answer
C++: Using type as map key introduces template substitution errors
I'm using a tuple as a key to track elements in a map, and then later iterating over the map to produce a string version of the map. To help me with the conversion, I have a template convenience function that will concatenate the tuple used as the…
sabreitweiser
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