A std::pair is an ordered, heterogeneous sequence of exactly two objects (it is a special case of std::tuple).
std::pair is a part of the C++ Standard Library, defined in the header <utility>.
Questions tagged [std-pair]
776 questions
713
votes
37 answers
What is the equivalent of the C++ Pair in Java?
Is there a good reason why there is no Pair in Java? What would be the equivalent of this C++ construct? I would rather avoid reimplementing my own.
It seems that 1.6 is providing something similar (AbstractMap.SimpleEntry), but this looks…
David Segonds
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338
votes
14 answers
What is C# analog of C++ std::pair?
I'm interested: What is C#'s analog of std::pair in C++? I found System.Web.UI.Pair class, but I'd prefer something template-based.
Thank you!
Alexander Prokofyev
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238
votes
7 answers
What is the purpose of std::make_pair vs the constructor of std::pair?
What is the purpose of std::make_pair?
Why not just do std::pair(0, 'a')?
Is there any difference between the two methods?
user542687
171
votes
9 answers
What is the preferred/idiomatic way to insert into a map?
I have identified four different ways of inserting elements into a std::map:
std::map function;
function[0] = 42;
function.insert(std::map::value_type(0, 42));
function.insert(std::pair(0,…
fredoverflow
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131
votes
6 answers
Difference between std::pair and std::tuple with only two members?
Is there a difference between an std::pair and an std::tuple with only two members? (Besides the obvious that std::pair requires two and only two members and tuple may have more or less...)
Casey
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86
votes
5 answers
How can I print out C++ map values?
I have a map like this:
map> myMap;
And I've inserted some data into my map using:
myMap.insert(make_pair(first_name, make_pair(middle_name, last_name)));
How can I now print out all the data in my map?
Zhi Rui
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78
votes
10 answers
How can I make an unordered set of pairs of integers in C++?
The following program does not compile an unordered set of pairs of integers, but it does for integers. Can unordered_set and its member functions be used on user-defined types, and how can I define it?
#include
...
class…
Pippi
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63
votes
11 answers
Use of for_each on map elements
I have a map where I'd like to perform a call on every data type object member function. I yet know how to do this on any sequence but, is it possible to do it on an associative container?
The closest answer I could find was this: Boost.Bind to…
Antonio Pérez
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61
votes
10 answers
Adding to a vector of pair
I have a vector of pair like such:
vector> revenue;
I want to add a string and a double from a map like this:
revenue[i].first = "string";
revenue[i].second = map[i].second;
But since revenue isn't initialized, it comes up with…
Richard
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56
votes
3 answers
Why was pair range access removed from C++11?
I just discovered that at one point, the C++11 draft had std::begin/std::end overloads for std::pair that allowed treating a pair of iterators as a range suitable for use in a range-based for loop (N3126, section 20.3.5.5), but this has since been…
HighCommander4
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55
votes
8 answers
converting a variable name to a string in C++
I'd like to output some data to a file. For example assume I have two vectors of doubles:
vector data1(10);
vector data2(10);
is there an easy way to output this to a file so that the first row contains the headings 'data1' and…
Wawel100
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53
votes
7 answers
What is the difference between std::list and std::map in C++ STL?
What is the difference between std::list and std::map? Is there a find method for the list, too?
Boolean
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47
votes
2 answers
Why is std::pair faster than std::tuple
Here is the code for testing.
Tuple test:
using namespace std;
int main(){
vector> v;
for (int var = 0; var < 100000000; ++var) {
v.push_back(make_tuple(var, var));
}
}
Pair test:
#include
using…
user4233758
45
votes
10 answers
What is std::pair?
What is std::pair for, why would I use it, and what benefits does boost::compressed_pair bring?
Anthony
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44
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1 answer
Why is std::pair from anonymous object copying that object instead of moving?
I tried to make std::pair with this style:
#include
struct A {
A() noexcept {
std::cout << "Created\n";
}
A(const A&) noexcept {
std::cout << "Copy\n";
}
A(A&&) noexcept {
std::cout <<…
Shamil Mukhetdinov
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