find_if(3C++)

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

NAME

find_if

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

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.

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