# Array algorithms in C++ STL (all_of, any_of, none_of, copy_n and iota)

• Difficulty Level : Easy
• Last Updated : 25 Oct, 2022

From C++11 onwards, some new and interesting algorithms are added in STL of C++. These algorithms operate on an array and are useful in saving time during coding and hence useful in competitive programming as well.
all_of() This function operates on whole range of array elements and can save time to run a loop to check each elements one by one. It checks for a given property on every element and returns true when each element in range satisfies specified property, else returns false.

## CPP

 `// C++ code to demonstrate working of all_of()``#include``#include // for all_of()``using` `namespace` `std;``int` `main()``{``    ``// Initializing array``    ``int` `ar[6] =  {1, 2, 3, 4, 5, -6};` `    ``// Checking if all elements are positive``    ``all_of(ar, ar+6, [](``int` `x) { ``return` `x>0; })?``          ``cout << "All are positive elements" :``          ``cout << "All are not positive elements";` `    ``return` `0;` `}`

Output:

`All are not positive elements`

Time Complexity: O(n)
Auxiliary Space: O(1)

In the above code, -6 being a negative element negates the condition and returns false.
any_of() This function checks for a given range if there’s even one element satisfying a given property mentioned in function. Returns true if at least one element satisfies the property else returns false.

## CPP

 `// C++ code to demonstrate working of any_of()``#include``#include // for any_of()``using` `namespace` `std;``int` `main()``{``    ``// Initializing array``    ``int` `ar[6] =  {1, 2, 3, 4, 5, -6};` `    ``// Checking if any element is negative``    ``any_of(ar, ar+6, [](``int` `x){ ``return` `x<0; })?``          ``cout << "There exists a negative element" :``          ``cout << "All are positive elements";` `    ``return` `0;` `}`

Output:

`There exists a negative element`

Time Complexity: O(n)
Auxiliary Space: O(1)

In above code, -6 makes the condition positive.
none_of() This function returns true if none of elements satisfies the given condition else returns false.

## CPP

 `// C++ code to demonstrate working of none_of()``#include``#include // for none_of()``using` `namespace` `std;``int` `main()``{``    ``// Initializing array``    ``int` `ar[6] =  {1, 2, 3, 4, 5, 6};` `    ``// Checking if no element is negative``    ``none_of(ar, ar+6, [](``int` `x){ ``return` `x<0; })?``          ``cout << "No negative elements" :``          ``cout << "There are negative elements";` `    ``return` `0;``}`

Output:

`No negative elements`

Time Complexity: O(n)
Auxiliary Space: O(1)

Since all elements are positive, the function returns true.
copy_n() copy_n() copies one array elements to new array. This type of copy creates a deep copy of array. This function takes 3 arguments, source array name, size of array and the target array name.

## CPP

 `// C++ code to demonstrate working of copy_n()``#include``#include // for copy_n()``using` `namespace` `std;``int` `main()``{``    ``// Initializing array``    ``int` `ar[6] =  {1, 2, 3, 4, 5, 6};` `    ``// Declaring second array``    ``int` `ar1[6];` `    ``// Using copy_n() to copy contents``    ``copy_n(ar, 6, ar1);` `    ``// Displaying the copied array``    ``cout << "The ``new` `array after copying is : ";``    ``for` `(``int` `i=0; i<6 ; i++)``       ``cout << ar1[i] << " ";` `    ``return` `0;` `}`

Output:

`The new array after copying is : 1 2 3 4 5 6`

Time Complexity: O(n)
Auxiliary Space: O(n)

In the above code, the elements of ar are copied in ar1 using copy_n()
iota() This function is used to assign continuous values to array. This function accepts 3 arguments, the array name, size, and the starting number.

## CPP

 `// C++ code to demonstrate working of iota()``#include``#include // for iota()``using` `namespace` `std;``int` `main()``{``    ``// Initializing array with 0 values``    ``int` `ar[6] =  {0};` `    ``// Using iota() to assign values``    ``iota(ar, ar+6, 20);` `    ``// Displaying the new array``    ``cout << "The ``new` `array after assigning values is : ";``    ``for` `(``int` `i=0; i<6 ; i++)``       ``cout << ar[i] << " ";` `    ``return` `0;` `}`

Output:

`The new array after assigning values is : 20 21 22 23 24 25`

Time Complexity: O(n)
Auxiliary Space: O(1)