mismatch


Category: algorithms	Component type: function

Prototype

Mismatch is an overloaded name; there are actually two mismatch functions.

template <class InputIterator1
class InputIterator2>
pair<InputIterator1
InputIterator2>
mismatch(InputIterator1 first1
InputIterator1 last1
InputIterator2 first2);

template <class InputIterator1
class InputIterator2

          class BinaryPredicate>
pair<InputIterator1
InputIterator2>
mismatch(InputIterator1 first1
InputIterator1 last1
InputIterator2 first2

         BinaryPredicate binary_pred);

Description

Mismatch finds the first position where the two ranges [first1 last1) and [first2 first2 + (last1 - first1)) differ. The two versions of mismatch use different tests for whether elements differ.

The first version of mismatch finds the first iterator i in [first1 last1) such that *i != *(first2 + (i - first1)). The return value is a pair whose first element is i and whose second element is *(first2 + (i - first1)). If no such iterator i exists the return value is a pair whose first element is last1 and whose second element is *(first2 + (last1 - first1)).

The second version of mismatch finds the first iterator i in [first1 last1) such that binary_pred(*i *(first2 + (i - first1)) is false. The return value is a pair whose first element is i and whose second element is *(first2 + (i - first1)). If no such iterator i exists the return value is a pair whose first element is last1 and whose second element is *(first2 + (last1 - first1)).

Definition

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

Requirements on types

For the first version:

InputIterator1 is a model of Input Iterator.
InputIterator2 is a model of Input Iterator.
InputIterator1's value type is a model of Equality Comparable.
InputIterator2's value type is a model of Equality Comparable.
InputIterator1's value type can be compared for equality with InputIterator2's value type.

For the second version:

InputIterator1 is a model of Input Iterator.
InputIterator2 is a model of Input Iterator.
BinaryPredicate is a model of Binary Predicate.
InputIterator1's value type is convertible to BinaryPredicate's first argument type.
InputIterator2's value type is convertible to BinaryPredicate's second argument type.

Preconditions

[first1 last1) is a valid range.
[first2 first2 + (last2 - last1)) is a valid range.

Complexity

Linear. At most last1 - first1 comparisons.

Example

int A1[] = { 3
1
4
1
5
9
3 };
int A2[] = { 3
1
4
2
8
5
7 };
const int N = sizeof(A1) / sizeof(int);

pair<int*
int*> result = mismatch(A1
A1 + N
A2);
cout << "The first mismatch is in position " << result.first - A1 << endl;
cout << "Values are: " << *(result.first) << "
" << *(result.second) << endl;