# rotate  Category: algorithms Component type: function

### Prototype

```template <class ForwardIterator>
inline ForwardIterator rotate(ForwardIterator first, ForwardIterator middle,
ForwardIterator last);
```

### Description

Rotate rotates the elements in a range. That is, the element pointed to by middle is moved to the position first, the element pointed to by middle + 1 is moved to the position first + 1, and so on. One way to think about this operation is that it exchanges the two ranges [first, middle) and [middle, last). Formally, for every integer n such that 0 <= n < last - first, the element *(first + n) is assigned to *(first + (n + (last - middle)) % (last - first)). Rotate returns first + (last - middle).

### Definition

Defined in the standard header algorithm, and in the nonstandard backward-compatibility header algo.h.

### Preconditions

• [first, middle) is a valid range.
• [middle, last) is a valid range. 

### Complexity

Linear. At most last - first swaps are performed. 

### Example

```char alpha[] = "abcdefghijklmnopqrstuvwxyz";
rotate(alpha, alpha + 13, alpha + 26);
printf("%s\n", alpha);
// The output is nopqrstuvwxyzabcdefghijklm
```

### Notes

 It follows from these two requirements that [first, last) is a valid range.

 Rotate uses a different algorithm depending on whether its arguments are Forward Iterators, Bidirectional Iterators, or Random Access Iterators. All three algorithms, however, are linear.