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
44
votes
6 answers
Using pair as key in a map (C++ / STL)
I want to use a pair from STL as a key of a map.
#include
#include
ccarpenterg
- 779
- 2
- 10
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40
votes
3 answers
C++ vector of pairs initialization
I have
vector< pair> myVec (N);
I want to have all pairs initialized to -1,-1.
MyNameIsKhan
- 2,594
- 8
- 36
- 56
36
votes
2 answers
How to initialize C++17 vector of pairs with optional element
In C++17, how do you declare and initialize a vector of pairs(or tuples) with an optional element?
std::vector > > vec1 = { {1, true},
{2, false},
…
Eugene
- 10,957
- 20
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36
votes
6 answers
What is the difference between using a struct with two fields and a pair?
What is the difference regarding memory allocation and efficiency between using a struct with two fields and a pair?
Tamara Wijsman
- 12,198
- 8
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- 82
35
votes
5 answers
struct with 2 cells vs std::pair?
Possible Duplicate:
What is the difference between using a struct with two fields and a pair?
Dear all,
I have a little question about pairs and struct. Is there any advantage to use a std::pair instead of a struct with two cells ?
I have used…
ThR37
- 3,965
- 6
- 35
- 42
35
votes
2 answers
How should I brace-initialize an std::array of std::pairs?
std::array, 2> ids = { { 0, 1 }, { 1, 2 } };
VS2013 error:
error C2440: 'initializing' : cannot convert from 'int' to 'std::pair' No constructor could take the source type, or constructor overload resolution was…
Neil Kirk
- 21,327
- 9
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- 91
33
votes
6 answers
Is there a way to easily handle functions returning std::pairs?
C++11 has function std::minmax_element which returns a pair of values. This, however, is quite confusing to handle and read, and produces an extra, later useless variable to pollute the scope.
auto lhsMinmax = std::minmax_element(lhs.begin(),…
Adam Hunyadi
- 1,890
- 16
- 32
33
votes
4 answers
std::pair vs struct with two int's
In an ACM example, I had to build a big table for dynamic programming. I had to store two integers in each cell, so I decided to go for a std::pair. However, allocating a huge array of them took 1.5 seconds:
std::pair…
Etan
- 17,014
- 17
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32
votes
1 answer
Does there exist something like std::tie for std::pair?
Eg with tuples:
#include // std::tuple, std::make_tuple, std::tie
int num;
char letter;
std::tuple num_letter;
num_letter = std::make_tuple(10, 'a');
std::tie(num, letter) = num_letter; // unpack num_letter into num and…
wrhall
- 1,288
- 1
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32
votes
2 answers
Pair inside priority queue
I am trying to store pairs in priority queue and I am using a compare function that compares second value of each pair.
#include
#include
#include
using namespace std;
class CompareDist
{
public:
bool…
g4ur4v
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- 32
- 57
31
votes
1 answer
why do i need to use piecewise_construct in map::emplace for single arg constructors of noncopyable objects?
The following code will not compile on gcc 4.8.2.
The problem is that this code will attempt to copy construct an std::pair which can't happen due to struct A missing copy and move constructors.
Is gcc failing here or am I missing…
oli_obk
- 28,729
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28
votes
4 answers
Does C++ provide a "triple" template, comparable to pair?
Does C++ have anything like std::pair but with 3 elements?
For example:
#include
triple array[10];
array[1].first = 1;
array[1].second = 2;
array[1].third = 3;
user3432317
- 309
- 1
- 3
- 3
28
votes
2 answers
Using std::tie as a range for loop target
I want to do something like the following:
//std::vector> someInitializingFunction();
{
TypeA a;
TypeB b;
for (std::tie(a, b) : someInitializingFunction()) {
// do stuff;
}
}
However, this is not valid code…
OmnipotentEntity
- 16,531
- 6
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- 96
28
votes
3 answers
Using pair as key for map
Based on a previous question, I am trying to create a map using a pair of integers as a key i.e. map, int> and I've found information on how to insert:
#include
#include
sccs
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26
votes
2 answers
Initializer list inside std::pair
This code:
#include
#include
std::pair, int> groups{ { "A", "B" }, 0 };
int main()
{
for (const auto& i : groups.first)
{
std::cout << i << '\n';
}
return…
rin
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