Search first subrange : search « STL Algorithms Non modifying sequence operations « C++ Tutorial

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/* 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 <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>

/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << ' ';
    }
    std::cout << std::endl;
}

/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}

using namespace std;

// checks whether an element is even or odd
bool checkEven (int elem, bool even)
{
    if (even) {
        return elem  2 == 0;
    }
    else {
        return elem  2 == 1;
    }
}

int main()
{
    vector<int> coll;

    INSERT_ELEMENTS(coll,1,9);
    PRINT_ELEMENTS(coll,"coll: ");

    /* arguments for checkEven()
     * - check for: ''even odd even''
     */
    bool checkEvenArgs[3] = { true, false, true };

    // search first subrange in coll
    vector<int>::iterator pos;
    pos = search (coll.begin(), coll.end(),       // range
                  checkEvenArgs, checkEvenArgs+3, // subrange values
                  checkEven);                     // subrange criterion

    // loop while subrange found
    while (pos != coll.end()) {
        // print position of first element
        cout << "subrange found starting with element "
             << distance(coll.begin(),pos) + 1
             << endl;

        // search next subrange in coll
        pos = search (++pos, coll.end(),              // range
                      checkEvenArgs, checkEvenArgs+3, // subr. values
                      checkEven);                     // subr. criterion
    }
}

coll: 1 2 3 4 5 6 7 8 9
subrange found starting with element 2
subrange found starting with element 4
subrange found starting with element 6