I came up with this code whilst answering this question.

Is there a simpler way of doing this using standard library?

I want to iterate over every object and do something with every other object.

For example, 4 values 1, 2, 3, 4 would pair like:

(1, 2), (1, 3), (1, 4)
(2, 3), (2, 4)
(3, 4)

Each value combines with every other value. None combine with themselves, and symmetric pairings are considered the same.

This might be useful in a collision system where you want to check every solid with every other.

template<typename Iter, typename Func>
void pair_wise(Iter it, Iter last, Func func) {
 while(it != last) {
 Iter other = it;
 ++other;
 while(other != last) {
 func(*it, *other);
 ++other;
 }
 ++it;
 }
}

Usage:

#include <iostream>
#include <vector>
int main() {
 std::vector<int> values = {1, 2, 3, 4};
 pair_wise(values.begin(), values.end(),
 [](int& lhs, int& rhs) {
 std::cout << "(" << lhs << ", " << rhs << ")\n";
 }); 
}

Output:

(1, 2)
(1, 3)
(1, 4)
(2, 3)
(2, 4)
(3, 4)

I came up with this code whilst answering this question.

Is there a simpler way of doing this using standard library?

I want to iterate over every object and do something with every other object.

For example, 4 values 1, 2, 3, 4 would pair like:

(1, 2), (1, 3), (1, 4)
(2, 3), (2, 4)
(3, 4)

Each value combines with every other value. None combine with themselves, and symmetric pairings are considered the same.

This might be useful in a collision system where you want to check every solid with every other.

template<typename Iter, typename Func>
void pair_wise(Iter it, Iter last, Func func) {
 while(it != last) {
 Iter other = it;
 ++other;
 while(other != last) {
 func(*it, *other);
 ++other;
 }
 ++it;
 }
}

Usage:

#include <iostream>
#include <vector>
int main() {
 std::vector<int> values = {1, 2, 3, 4};
 pair_wise(values.begin(), values.end(),
 [](int& lhs, int& rhs) {
 std::cout << "(" << lhs << ", " << rhs << ")\n";
 }); 
}

Output:

(1, 2)
(1, 3)
(1, 4)
(2, 3)
(2, 4)
(3, 4)

I came up with this code whilst answering this question.

Is there a simpler way of doing this using standard library?

I want to iterate over every object and do something with every other object.

For example 4 values 1, 2, 3, 4 would pair like:

(1, 2), (1, 3), (1, 4)
(2, 3), (2, 4)
(3, 4)

Each value combines with every other value. None combine with themselves, and symmetric pairings are considered the same.

This might be useful in a collision system where you want to check every solid with every other.

template<typename Iter, typename Func>
void pair_wise(Iter it, Iter last, Func func) {
 while(it != last) {
 Iter other = it;
 ++other;
 while(other != last) {
 func(*it, *other);
 ++other;
 }
 ++it;
 }
}
#include <iostream>
#include <vector>
int main() {
 std::vector<int> values = {1,2,3,4};
 pair_wise(values.begin(), values.end(),
 [](int& lhs, int& rhs) {
 std::cout << "(" << lhs << ", " << rhs << ")\n";
 }); 
}

Output:

(1, 2)
(1, 3)
(1, 4)
(2, 3)
(2, 4)
(3, 4)

I came up with this code whilst answering this question.

Is there a simpler way of doing this using standard library?

I want to iterate over every object and do something with every other object.

For example, 4 values 1, 2, 3, 4 would pair like:

(1, 2), (1, 3), (1, 4)
(2, 3), (2, 4)
(3, 4)

Each value combines with every other value. None combine with themselves, and symmetric pairings are considered the same.

This might be useful in a collision system where you want to check every solid with every other.

template<typename Iter, typename Func>
void pair_wise(Iter it, Iter last, Func func) {
 while(it != last) {
 Iter other = it;
 ++other;
 while(other != last) {
 func(*it, *other);
 ++other;
 }
 ++it;
 }
}

Usage:

#include <iostream>
#include <vector>
int main() {
 std::vector<int> values = {1,2,3,4};
 pair_wise(values.begin(), values.end(),
 [](int& lhs, int& rhs) {
 std::cout << "(" << lhs << ", " << rhs << ")\n";
 }); 
}

Output:

(1, 2)
(1, 3)
(1, 4)
(2, 3)
(2, 4)
(3, 4)