The sample code below illustrates how to use the abs STL
function in Visual C++.
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Required Header
<valarray>
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Prototype
template<class T>
valarray<T> abs(const valarray<T>& x);
: The class/parameter names in the prototype may not match the
version in the header file. Some have been modified to improve readability.
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Description
The sample declares a valarray of integers and uses STL abs()
function to get the absolute value for each array element.
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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
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For the same information about abs, visit the following
MSDN Web site:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vcsampsampleabsstlsample.asp (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcstdlib/html/vcsampsampleabsstlsample.asp)Back to the top
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