# Man Page find_first_of.3

```
Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.

```

## NAME

```     find_first_of

- Finds the first occurrence of any value from one sequence
in another sequence.

```

## SYNOPSIS

```     #include <algorithm>
template <class ForwardIterator1, class ForwardIterator2>
ForwardIterator1 find_first_of (ForwardIterator1 first1,
ForwardIterator1 last1,
ForwardIterator2 first2,
ForwardIterator2 last2);

template <class ForwardIterator1, class ForwardIterator2,
class BinaryPredicate>
ForwardIterator1 find_first_of (ForwardIterator1 first1,
ForwardIterator1 last1,
ForwardIterator2 first2,
ForwardIterator2 last2,
BinaryPredicate pred);

```

## DESCRIPTION

```     The find_first_of algorithm finds the first occurrence of  a
value  from  a  sequence,  specified  by first2, last2, in a
sequence specified by first1, last1. The  algorithm  returns
an  iterator in the range [first1, last1) that points to the
first matching  element.  If  the  first  sequence  [first1,
last1)  does  not  contain  any  of the values in the second
sequence, find_first_of returns last1.

In other words, find_first_of returns the first  iterator  i
in  the  [first1,  last1)such that for some integer j in the
range [first2, last2), the following conditions hold:

*i == *j, pred(*i,*j) == true.

Or find_first_of returns last1 if no such iterator is found.

Two versions of the algorithm  exist.  The  first  uses  the
equality  operator  as the default binary predicate, and the
second allows you to specify a binary predicate.

```

## COMPLEXITY

```     At most (last1 - first1)*(last2 -  first2)  applications  of
the corresponding predicate are done.

```

## EXAMPLE

```     //
// find_f_o.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};
int d2[2] = {6,4};
//
// Set up two vectors
//
vector<int> v1(d1,d1 + 10), v2(d2,d2 + 2);
//
// Try both find_first_of variants
//
iterator it1 =
find_first_of(v1.begin(),v1.end(),v2.begin(),v2.end());
find_first_of(v1.begin(),v1.end(),v2.begin(),v2.end(),
equal_to<int>());
//
// Output results
//
cout << "For the vectors: ";
copy(v1.begin(),v1.end(),
ostream_iterator<int,char>(cout," " ));
cout << " and ";
copy(v2.begin(),v2.end(),
ostream_iterator<int,char>(cout," " ));
cout << endl << endl
<< "both versions of find_first_of point to: "
<< *it1;

return 0;

}

Program Output

For the vectors: 0 1 2 2 3 4 2 2 6 7  and 6 4
both versions of find_first_of point to: 4

```

## WARNINGS

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

vector<int, allocator<int> >

vector<int>

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

```

```     Algorithms, adjacent_find, find, find_if, find_end

```