A simple program interprets the C ++ STL algorithm series 3: find_if

 

C ++ STL's Non-mutating algorithms is a set of template functions that do not destroy operation data, it is used for processing sequence data one by one, element search, subsequence search, statistics, and matching.

 

The find_if algorithm is a predicate version of the find algorithm. It uses the predicates that return boolean values to determine the pred and checks every element in the iterator range [first, last, if the iterator iter satisfies pred (* iter) = true, the element is found and the iterator value iter is returned. If no element is found, the last is returned.

 

Function prototype:

 

 

Template <class InputIterator, class Predicate>

InputIterator find_if (

InputIterator _ First,

InputIterator _ Last,

Predicate _ Pred

);

 

Sample Code:

 

 

/*************************************** ****************************

* Copyright (C) Jerry Jiang

* File Name: find_if.cpp

* Author: Jerry Jiang

* Create Time: 2011-9-29 22:21:29

* Mail: jbiaojerry@gmail.com

* Blog: http://blog.csdn.net/jerryjbiao

* Description: The third in the C ++ STL algorithm series interpreted by a simple program.

* Non-variable algorithm: Conditional search for the container element find_if

**************************************** **************************/

 

# Include <algorithm>

# Include <vector>

# Include <iostream>

 

Using namespace std;

 

// The predicate judgment function divbyfive: determines whether x can divide x by 5.

Bool divbyfive (int x)

{

Return x % 5? 0: 1;

}

 

Int main ()

{

// Initial vector

Vector <int> iVect (20 );

For (size_t I = 0; I <iVect. size (); ++ I)

{

IVect [I] = (I + 1) * (I + 3 );

}

 

Vector <int>: iterator iLocation;

ILocation = find_if (iVect. begin (), iVect. end (), divbyfive );

 

If (iLocation! = IVect. end ())

{

Cout <"the first element that can be divisible by 5 is :"

<* ILocation <endl // print element: 15

<"The index position of an element is :"

<ILocation-iVect. begin () <endl; // print the index location: 2

}

Return 0;

}

From: Jerry Jiang's program life