usefcnptr.cpp

C++Primer 第四版 包括windows 平台下各章的例子程序

/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 * 
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 * 
 * 
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 * 
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address: 
 * 
 * 	Pearson Education, Inc.
 * 	Rights and Contracts Department
 * 	75 Arlington Street, Suite 300
 * 	Boston, MA 02216
 * 	Fax: [phone]
*/ 

#include <iostream>
#include <vector>
using std::vector;
using std::endl;
using std::cout;

// function to return minimum element in an vector of ints
int min_element(vector<int>::iterator, 
                vector<int>::iterator);

// pointer to function, initialized to point to min_element
int (*pf)(vector<int>::iterator, vector<int>::iterator) 
        = min_element;

int main() 
{
    vector<int> ivec;
    // give ivec some values
    for (vector<int>::size_type i = 0; i < 10; ++i)
        ivec.push_back(i);

    cout << "Direct call: "   
         << min_element(ivec.begin(), ivec.end()) << endl;

    cout << "Indirect call: " 
         << pf(ivec.begin(), ivec.end()) << endl;

    return 0;
}

// returns minimum element in an vector of ints
int min_element(vector<int>::iterator beg, 
                vector<int>::iterator end) {
    int minVal = 0;
    while (beg != end) {
        if (minVal > *beg)
            minVal = *beg;
        ++beg;
    }
    return minVal;
}