## find_if

    Algorithm

- Summary
- Data Type and Member Function Indexes
- Synopsis
- Description
- Complexity
- Example
- Warnings
- See Also

### Summary

Finds an occurrence of a value in a sequence that satisfies a specified predicate.

### Data Type and Member Function Indexes
(exclusive of constructors and destructors)

None

### Synopsis

    #include <algorithm>
    template <class InputIterator, class Predicate>
      InputIterator find_if(InputIterator first,
                            InputIterator last,
                            Predicate pred);

### Description

The find_if algorithm allows you to search for the first element in a sequence that satisfies a particular condition. The sequence is defined by iterators `first` and `last`, while the condition is defined by the third argument: a predicate function that returns a boolean value. find_if returns the first iterator `i` in the range `[first, last)` for which the following condition holds:

`pred(*i) == true.`

If no such iterator is found, find_if returns `last`.

### Complexity

find_if performs at most `last-first` applications of the corresponding predicate.

### Example

    /
    // find.cpp
    //
    #include <vector>
    #include <algorithm>
    #include <functional>
    #include <iostream>
    using namespace std;

    int main()
     {
       typedef vector<int>::iterator iterator;
       int d1[10] = {0,1,2,2,3,4,2,2,6,7};

       // Set up a vector
       vector<int> v1(d1,d1 + 10);

       // Try find
       iterator it1 = find(v1.begin(),v1.end(),3);
       // it1 = v1.begin() + 4;

       // Try find_if
       iterator it2 =
        find_if(v1.begin(),v1.end(),bind1st(equal_to<int>(),3));
       // it2 = v1.begin() + 4

       // Try both adjacent_find variants
       iterator it3 = adjacent_find(v1.begin(),v1.end());
       // it3 = v1.begin() +2

       iterator it4 =
          adjacent_find(v1.begin(),v1.end(),equal_to<int>());
       // v4 = v1.begin() + 2

       // Output results
       cout << *it1 << " " << *it2 << " " << *it3 << " "
            << *it4 << endl;

       return 0;
     }

Program Output

    3 3 2 2

### Warnings

If your compiler does not support default template parameters, then you always need to supply the `Allocator` template argument. For instance, you have to write:

`vector<int, allocator<int> >`

instead of:

`vector<int>`

If your compiler does not support namespaces, then you do not need the using declaration for `std`.

### See Also

adjacent_find, Algorithms, find,find_end, find_first_of

Copyright (c) 1998, Rogue Wave Software, Inc.
Send mail to report errors or comment on the documentation.
OEM Release, June 1998