DOCUMENT:Q156299  07-MAY-2001  [visualc]
TITLE   :STL Sample for the find_if Function
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:
OPER/SYS:
KEYWORDS:_IK

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The information in this article applies to:

 - The Standard C++ Library, included with:
    - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, version 4.2 
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SUMMARY
=======

The sample code below illustrates how to use the find_if STL function in Visual
C++.

MORE INFORMATION
================

Required Header
---------------

   <algorithm>
    

Prototype
---------

      template<class InputIterator, class T, class Predicate> inline
               InputIterator find_if(InputIterator first,
                                     InputIterator last,
                                     Predicate predicate)

NOTE: The class/parameter names in the prototype do not match the version in the
header file. Some have been modified to improve readability.

Description
-----------

The find_if algorithm locates the first element in the range [first, last) that
causes the predicate to return true and returns the iterator positioned at that
element, or last if no such element was found.

Sample Code
-----------

   ////////////////////////////////////////////////////////////////////// 
   // 
   // Compile options needed: /GX
   // 
   // findif.cpp : Illustrates how to use the find_if function.
   // 
   // Functions:
   // 
   //   find_if  - locate the first element in a range that satisfies
   //              a predicate.
   // 
   // Written by Kalindi Sanghrajka
   // of Microsoft Product Support Services,
   // Software Core Developer Support.
   // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
   ////////////////////////////////////////////////////////////////////// 

   // disable warning C4786: symbol greater than 255 character,
   // okay to ignore
   #pragma warning(disable: 4786)

   #include <algorithm>
   #include <iostream>
   using namespace std;

   // returns true if n is an odd number
   int IsOdd( int n)
   {
       return n % 2 ;
   }

   void main()
   {
       const int ARRAY_SIZE = 8 ;
       int IntArray[ARRAY_SIZE] = { 1, 2, 3, 4, 4, 5, 6, 7 } ;
       int *location ;   // stores the position of the first
                         // element that is an odd number
       int i ;

           // print content of IntArray
       cout << "IntArray { " ;
       for(i = 0; i < ARRAY_SIZE; i++)
           cout << IntArray[i] << ", " ;
       cout << " }" << endl ;

       // Find the first element in the range [first, last -1 ]
       // that is an odd number
       location = find_if(IntArray, IntArray + ARRAY_SIZE, IsOdd) ;

       //print the location of the first element
       // that is an odd number
       if (location != IntArray + ARRAY_SIZE)  // first odd element found
           cout << "First odd element " << *location
                << " is at location " << location - IntArray << endl;
       else         // no odd numbers in the range
           cout << "The sequence does not contain any odd numbers"
                << endl ;
       }

Output:

IntArray { 1, 2, 3, 4, 4, 5, 6, 7, }

First odd element 1 is at location 0

REFERENCES
==========

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL count_if

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Keywords          : _IK 
Technology        : kbVCsearch kbAudDeveloper kbVCLibrary
Version           : winnt:
Issue type        : kbhowto

=============================================================================

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