Microsoft KB Archive/156299

= STL Sample for the find_if Function =

Article ID: 156299

Article Last Modified on 12/10/2003

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APPLIES TO

 The Standard C++ Library, when used with:  Microsoft Visual C++ 4.2 Professional Edition

 Microsoft Visual C++ 4.2 Enterprise Edition

 Microsoft Visual C++ 5.0 Learning Edition 

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This article was previously published under Q156299

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

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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
 * 1) pragma warning(disable: 4786)

using namespace std;
 * 1) include
 * 2) include

// 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

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