Use function defined in a namespace : namespace « Language Basics « C++ Tutorial

Home
C++ Tutorial
1.Language Basics
2.Data Types
3.Operators statements
4.Array
5.Development
6.Exceptions
7.Function
8.Structure
9.Class
10.Operator Overloading
11.Pointer
12.File Stream
13.template
14.STL Introduction
15.string
16.vector
17.list
18.bitset
19.set multiset
20.valarray
21.queue stack
22.deque
23.map multimap
24.STL Algorithms Modifying sequence operations
25.STL Algorithms Non modifying sequence operations
26.STL Algorithms Binary search
27.STL Algorithms Sorting
28.STL Algorithms Merge
29.STL Algorithms Min Max
30.STL Algorithms Iterator
31.STL Algorithms Heap
32.STL Algorithms Helper
C / ANSI-C
C Tutorial
C++
Visual C++ .NET
C++ Tutorial » Language Basics » namespace 
1.9.11.Use function defined in a namespace
/* 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 <cstdlib>

namespace MyLib {
    double readAndProcessSum (std::istream&);
}

int main()
{
    using namespace std;
    double sum;

    try {
        sum = MyLib::readAndProcessSum(cin);
    }
    catch (const ios::failure& error) {
        cerr << "I/O exception: " << error.what() << endl;
        return EXIT_FAILURE;
    }
    catch (const exception& error) {
        cerr << "standard exception: " << error.what() << endl;
        return EXIT_FAILURE;
    }
    catch (...) {
        cerr << "unknown exception" << endl;
        return EXIT_FAILURE;
    }

    // print sum
    cout << "sum: " << sum << endl;
}

#include <istream>

namespace MyLib {
    double readAndProcessSum (std::istream& strm)
    {
        double value, sum;

        /* while stream is OK
         * - read value and add it to sum
         */
        sum = 0;
        while (strm >> value) {
            sum += value;
        }

        if (!strm.eof()) {
            throw std::ios::failure
                    ("input error in readAndProcessSum()");
        }

        // return sum
        return sum;
    }
}
a
I/O exception: input error in readAndProcessSum()
1.9.namespace
1.9.1.A namespace
1.9.2.Use a namespace
1.9.3.A nested namespace
1.9.4.Reuse namespace
1.9.5.Reference variables in namespaces
1.9.6.using namespace in program block
1.9.7.Reference global variable, variable in the nested namespace
1.9.8.Use Namespace to organize functions
1.9.9.function in a namespace reference variables in the same namespace
1.9.10.using namespace std;
1.9.11.Use function defined in a namespace
1.9.12.Using unnamed namespaces.
1.9.13.Using namespace aliases
1.9.14.Using the using directive
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.