# swap_ranges

 Category: algorithms Component type: function

### Prototype

```template <class ForwardIterator1, class ForwardIterator2>
ForwardIterator2 swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1,
ForwardIterator2 first2);
```

### Description

Swap_ranges swaps each of the elements in the range [first1, last1) with the corresponding element in the range [first2, first2 + (last1 - first1)). That is, for each integer n such that 0 <= n < (last1 - first1), it swaps *(first1 + n) and *(first2 + n). The return value is first2 + (last1 - first1).

### Definition

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

### Requirements on types

ForwardIterator1 and ForwardIterator2 must both be models of Forward Iterator. The value types of ForwardIterator1 and ForwardIterator2 must be convertible to each other.

### Preconditions

• [first1, last1) is a valid range.
• [first2, first2 + (last1 - first1)) is a valid range.
• The two ranges [first1, last1) and [first2, first2 + (last1 - first1)) do not overlap.

### Complexity

Linear. Exactly last1 - first1 swaps are performed.

### Example

```vector<int> V1, V2;
V1.push_back(1);
V1.push_back(2);
V2.push_back(3);
V2.push_back(4);

assert(V1[0] == 1 && V1[1] == 2 && V2[0] == 3 && V2[1] == 4);
swap_ranges(V1.begin(), V1.end(), V2.begin());
assert(V1[0] == 3 && V1[1] == 4 && V2[0] == 1 && V2[1] == 2);
```

### See also

swap, iter_swap.

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