use generic function as predicate : predicate « STL Basics « C++

1. C++
2. STL Basics
3. predicate

use generic function as predicate

 
 

/* The following code example is taken from the book
 * "C++ Templates - The Complete Guide"
 * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
 *
 * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
using namespace std;

template <typename T, int VAL>
T addValue (T const& x)
{
    return x + VAL;
}


void call_addValue()
{
    addValue<int,5>(42);
}

template <typename IT, typename OP>
void transform (IT beg, IT end, IT to, OP op)
{
    while (beg != end) {
        *to++ = op(*beg++);
    }
}

int main()
{
    call_addValue();

    int m[] = { 1, 2, 3, 4, 5, 6 };

    transform (m, m+6,
               m,
               (int(*)(int const&))    // cast necessary
               addValue<int,5>);

    for(int i=0;i<6;i++){
       cout << m[i] << " ";
    }
}
/* 
6 7 8 9 10 11
 */
        
  

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