STL Sample for Basic Math Functions

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

SUMMARY

The sample code below illustrates how to use basic math STL functions plus, minus, divides, times, and modulus in Visual C++.

MORE INFORMATION

Required Header

   < functional >

Prototype

   template<class _TYPE>
   struct plus : binary_function<_TYPE, _TYPE, _TYPE>
   {
     _TYPE operator()(const _TYPE& _X, const _TYPE& _Y) const
                                         {return (_X + _Y); }
   };
   template<class _TYPE>
   struct minus : binary_function<_TYPE, _TYPE, _TYPE>
   {
     _TYPE operator()(const _TYPE& _X, const _TYPE& _Y) const
                                         {return (_X - _Y); }
   };
   template<class _TYPE>
   struct times : binary_function<_TYPE, _TYPE, _TYPE>
   {
     _TYPE operator()(const _TYPE& _X, const _TYPE& _Y) const
                                         {return (_X * _Y); }
   };
   template<class _TYPE>
   struct divides : binary_function<_TYPE, _TYPE, _TYPE>
   {
     _TYPE operator()(const _TYPE& _X, const _TYPE& _Y) const
                                         {return (_X / _Y); }
   };
   template<class _TYPE>
   struct modulus : binary_function<_TYPE, _TYPE, _TYPE>
   {
     _TYPE operator()(const _TYPE& _X, const _TYPE& _Y) const
                                         {return (_X % _Y); }
   };

Description

This sample uses a class derived from all 5 basic math structures: plus, minus, times, divides, and modulus, using an integer as the templated operand.

Sample Code

////////////////////////////////////////////////////////////////
//
// Compile options needed: none
//
// mathfunc.cpp - Illustrating the basic STL math
//                functions.
//
// Structures: plus<A>    - Adds data type A object to
//                          a class object derived from plus.
//             minus<A>   - Subtracts data type A.
//             times<A>   - Multiplies object by data type A.
//             divides<A> - Divides object by data type A.
//             modulus<A> - Returns object modulo A.
//
// Written by Mark Hagen
// of Microsoft Product Support Services,
// Copyright (c) 1996 Microsoft Corporation.
// All rights reserved.
/////////////////////////////////////////////////////////////////

#include <functional>

                 public times<int>, public divides<int>,
                 public modulus<int>
{

  int value;
  MathOps(){value=0;}
  MathOps(int x){value=x;}
  result_type operator+(second_argument_type add2)
                            {return value + add2;}
  result_type operator-(second_argument_type sub2)
                            {return value - sub2;}
  result_type operator*(second_argument_type mult2)
                            {return value * mult2;}
  result_type operator/(second_argument_type div2)
                            {return value / div2;}
  result_type operator%(second_argument_type mod2)
                            {return value % mod2;}
};

void main(void)

  MathOps one,two,three,four,five,six;

  cout << "Using MathOps class..." << endl ;

  one = 18;
  cout << "one = " << one << endl ;

  two = one + 1;
  cout << "two = one + 1 = " << two << endl ;

  three = two - 2;
  cout << "three = two - 2 = " << three << endl ;

  four = three * 3;
  cout << "four = three * 3 = " << four << endl ;

  five = four / 4;
  cout << "five = four / 4 = " << five << endl ;

  six = five % 5;
  cout << "six = five % 5 = " << six << endl ;

Program Output is:

Using MathOps class... one = 18 two = one + 1 = 19 three = two - 2 = 17 four = three * 3 = 51 five = four / 4 = 12 six = five % 5 = 2

REFERENCES

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