C++ Algorithm reverse()

C++ Algorithm reverse() function is used to reverse the order of the elements within a range [first, last).

Syntax

Note: BidirectionalIterator is an iterator which is used to access any elements of a container in both forward and backward direction.

Parameter

first: A bidirectional iterator pointing the position of the first element in the range in which the elements are being reversed.

last: A forward iterator pointing the position one past the final element in the range in which the elements are being reversed.

Return value

None

Complexity

Complexity is linear in the range [first, last): swaps elements.

Data races

The object in the range [first, last) are modified.

Exceptions

This function throws an exception if either an element is swapped or an operation on iterator throws an exception.

Note: The invalid parameters cause an undefined behavior.

Example 1

Let's see the simple example to reverse the given string:

Output:

Before Reverse : Hello Myself Nikita
After Reverse   : atikiN flesyM olleH

Example 2

Let's see another simple example to reverse the range of numbers:

Output:

The original vector v1 is:
 ( 0 1 2 3 4 5 6 7 8 9 ).
The modified vector v1 with values reversed is:
 ( 9 8 7 6 5 4 3 2 1 0 ).

Example 3

Let's see another simple example:

Output:

Before: 10 11 12 13 14 15 16 17 

Reverse only from index 5 to 7 in array:
10 11 12 13 14 17 16 15 
Reverse full array:
7654

Example 4

Let's see another simple example:

Output:

Original order : 1. George  2.  John  3.   Nik  4. Alice  5.   Bob  6. Watson  

Reversing the order ....
Reversed order : 1. Watson  2.   Bob  3. Alice  4.   Nik  5.  John  6. George