Use predicate, which returns whether an integer is a prime number, with a list : predicate « STL Introduction « C++ Tutorial






/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * 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>
#include <list>
#include <algorithm>
#include <cstdlib>      // for abs()
using namespace std;

// predicate, which returns whether an integer is a prime number
bool isPrime (int number)
{
    // ignore negative sign
    number = abs(number);

    // 0 and 1 are no prime numbers
    if (number == 0 || number == 1) {
        return false;
    }
        
    // find divisor that divides without a remainder
    int divisor;
    for (divisor = number/2; numberdivisor != 0; --divisor) {
        ;
    }

    // if no divisor greater than 1 is found, it is a prime number
    return divisor == 1;
}

int main()
{
    list<int> coll;

    // insert elements from 24 to 30
    for (int i=24; i<=30; ++i) {
        coll.push_back(i);
    }

    // search for prime number
    list<int>::iterator pos;
    pos = find_if (coll.begin(), coll.end(),    // range
                   isPrime);                    // predicate
    if (pos != coll.end()) {
        // found
        cout << *pos << " is first prime number found" << endl;
    }
    else {
        // not found
        cout << "no prime number found" << endl;
    }
}
29 is first prime number found








14.9.predicate
14.9.1.Create your own unary function
14.9.2.use generic function as predicate
14.9.3.Function object to process the mean value
14.9.4.Illustrating the use of an adaptor for pointers to functions
14.9.5.Use predicate, which returns whether an integer is a prime number, with a list
14.9.6.Convenience function for the compose_f_gx adapter
14.9.7.Convenience function for the compose_f_gx_hx adapter
14.9.8.Convenience function for the compose_f_gx_hy adapter