Q156811: INFO: STL Sample for the abs Function

Article: Q156811
Product(s): Microsoft C Compiler
Version(s): 4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbVC420 kbVC500 kbVC600 kbDSupport
Last Modified: 27-MAR-2002

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The information in this article applies to:

- The Standard C++ Library, used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
   - Microsoft Visual C++.NET (2002) 
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SUMMARY
=======

The sample code below illustrates how to use the abs STL function in Visual C++.

MORE INFORMATION
================

Required Header
---------------

     <valarray>

Prototype
---------

     template<class T>
     valarray<T> abs(const valarray<T>& x);

NOTE: The class/parameter names in the prototype may not match the version in the
header file. Some have been modified to improve readability.

Description
-----------

The sample declares a valarray of integers and uses STL abs() function to get the
absolute value for each array element.

Sample Code
-----------

NOTE: The first line in the sample code section says:

  // Compile options needed: /GX

In VC++ .NET, /EHsc is set by default and is equivalent to /GX.

  ////////////////////////////////////////////////////////////////////// 
  // 
  // Compile options needed: None
  // 
  // <filename> :  main.cpp
  // 
  // Functions:
  // 
  //    abs
  // 
  // Written by Yeong-Kah Tam
  // of Microsoft Product Support Services,
  // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
  ////////////////////////////////////////////////////////////////////// 

  // disable warning C4267: possible loss of data,
  // okay to ignore

  #pragma warning(disable: 4267)

  #include <iostream>                 // for i/o functions
  #include <valarray>                 // for valarray

  #if _MSC_VER > 1020   // if VC++ version is > 4.2
     using namespace std;  // std c++ libs implemented in std
     #endif

  #define ARRAY_SIZE  10              // array size

  typedef valarray<int> INTVALARRAY;  // type for valarray of ints

  void main()

  {

      // Initialize val_array to 0, -1, -2, etc.
      INTVALARRAY val_array(ARRAY_SIZE);
      for (int i = 0; i < ARRAY_SIZE; i++)
          val_array[i] = -i;

      // Display the size of val_array.
      cout << "Size of val_array = " << val_array.size() << "\n\n";

      // Display the values of val_array before calling abs().
      cout << "The values of val_array before calling abs():\n";
      for (i = 0; i < ARRAY_SIZE; i++)
          cout << val_array[i] << "    ";
      cout << "\n\n";

      // Display the result of val_array after calling abs().
      INTVALARRAY abs_array = abs(val_array);
      cout << "The result of val_array after calling abs():\n";
      for (i = 0; i < ARRAY_SIZE; i++)
          cout << abs_array[i] << "     ";
      cout << "\n\n";

  }

Output:

Size of val_array = 10

The values of val_array before calling abs():
0    -1    -2    -3    -4    -5    -6    -7    -8    -9

The result of val_array after calling abs():
0     1     2     3     4     5     6     7     8     9

REFERENCES
==========

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL STLSample abs

======================================================================
Keywords          : kbcode kbVC420 kbVC500 kbVC600 kbDSupport 
Technology        : kbVCsearch kbAudDeveloper kbVCLibrary
Version           : :4.2,5.0,6.0
Issue type        : kbinfo

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