STL Sample for the abs Function

ID: Q156811

The information in this article applies to:

The Standard C++ Library included with: - Microsoft Visual C++, 32-bit Edition, version 4.2

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

////////////////////////////////////////////////////////////////////// 
// 
// 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.
////////////////////////////////////////////////////////////////////// 

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

#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.length() << "\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 STLIss 
Version           : WINNT:4.2;
Platform          : NT WINDOWS
Issue type        : kbhowto

Last Reviewed: October 10, 1997