Convert an array to a list in C++
This post will discuss how to convert an array to a list in C++.
1. Using Range Constructor
A simple solution is to use the range constructor of std::list, which constructs a new list initialized by elements of the specified range (defined by two input iterators).
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#include <iostream> #include <list> int main() { int arr[] = { 10, 15, 20, 25 }; std::list<int> ints(std::begin(arr), std::end(arr)); // or, use // std::list<int> ints(arr, arr + sizeof(arr)/sizeof(int)); for (int i: ints) { std::cout << i << " "; } return 0; } |
Output:
10 15 20 25
2. Using std::insert function
For an existing list, we can use the overloaded std::insert function that takes three parameters. The first parameter is an iterator to the destination list. The second and third parameters are the iterators specifying a range of the array elements.
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#include <iostream> #include <list> int main() { int arr[] = { 10, 15, 20, 25 }; std::list<int> ints; ints.insert(ints.begin(), std::begin(arr), std::end(arr)); // or, use // ints.insert(ints.begin(), arr, arr + sizeof(arr)/sizeof(int)); for (int i: ints) { std::cout << i << " "; } return 0; } |
Output:
10 15 20 25
3. Using range-based for-loop
We can also use the range-based for-loop that loops through the array elements and adds each encountered element to the list using list::push_back.
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#include <iostream> #include <list> int main() { int arr[] = { 10, 15, 20, 25 }; std::list<int> ints; for (int i: arr) { ints.push_back(i); } for (int i: ints) { std::cout << i << " "; } return 0; } |
Output:
10 15 20 25
4. Using std::copy function
Another solution is to use the std::copy, which copies the specified range of elements to another range beginning from the specified output iterator.
We can either use std::back_inserter to the initial position in the destination list that calls the push_back() function behind the scenes. If the list has enough storage, we can simply specify the output iterator to the beginning of the destination range.
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#include <iostream> #include <list> #include <iterator> #include <algorithm> int main() { int arr[] = { 10, 15, 20, 25 }; std::list<int> ints; std::copy(std::begin(arr), std::end(arr), std::back_inserter(ints)); // or, use // int n = sizeof(arr) / sizeof(arr[0]); // std::list<int> ints(n); // std::copy(arr, arr + n, ints.begin()); for (int i: ints) { std::cout << i << " "; } return 0; } |
Output:
10 15 20 25
5. Using std::assign function
We can also use the std::assign function that replaces the existing contents of the list with elements of the specified range.
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#include <iostream> #include <list> int main() { int arr[] = { 10, 15, 20, 25 }; std::list<int> ints; ints.assign(std::begin(arr), std::end(arr)); // or, use // int n = sizeof(arr)/sizeof(int); // ints.assign(arr, arr + n); for (int i: ints) { std::cout << i << " "; } return 0; } |
Output:
10 15 20 25
That’s all about converting an array to a list in C++.
Thanks for reading.
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