Re: [Dev-C++] PLEASE HELP: a prgm not working
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Re: [Dev-C++] PLEASE HELP: a prgm not working
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From: Jason H. <jas...@bt...> - 2001-10-20 01:47:57
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Hi, to sum it all up... you haven't performed any operations on the rational
objects p, s, t, & f. They still have the values they were initialised with,
which was zero. You will need to do the relavant ops on each i.e. p = add(a,
b);
I've created a header and cpp file from the code you supplied and added the
relevant bits. I've also slightly changed some of the definitions to make
them follow a what I think would be a slightly better approach. All I've
done is inlined some of the methods of rational, and added const to the
methods that won't change any of the values of the object. This is wise as
it helps prevent possible errors if you modify those methods in future.
I have also added some comments to where I think you need to take a look at
what you are trying to do (the reduce method). I hope they are useful to
you.
Regards, Jason.
----- Original Message -----
From: "chromatonus 712" <chr...@ho...>
To: <dev...@li...>
Sent: Saturday, October 20, 2001 12:52 AM
Subject: [Dev-C++] PLEASE HELP: a prgm not working
> hi, this program is supposed to add, subtract, multiply and divide two
> fractions and simplify the answers, using class objects. But the prgm
> displays 0/0 for the sums, differences, etc. How can I fix this program?
> THank you for your time :)
>
>
> #include <iostream.h>
> #include <conio.h>
> #include <stdlib.h>
>
>
> //=============================== CLASS HEADER
> ===============================
>
> class rational
> {
> public:
> // constructors
> rational();
> rational( int n, int d );
> // accessors
> int get_numerator();
> int get_denominator();
> // modifiers
> void change_numerator(int n);
> void change_denominator(int d);
> // enter from keyboard
> void enter();
> // precondition: two numbers are sent in for each rational
> number
> // postcondition: they are stored as two rational numbers
> // display
> void display();
>
> void reduce(int pn, int pd, int sn, int sd, int tn, int td,
int
> fn, int fd);
> // precondition: send in rational @n/@d (@ meaning an operation)
> // postcondition: calculate d = gcd(@n,@d)
> // reset @n = @n/d and @d = @d/d
>
> private:
> int my_numerator,my_denominator;
> };
>
> //============================FREE FUNCTIONS
> ==================================
>
> // assignment operator
> void assign( rational a , rational &b );
> // precondition: rational number a is sent in
> // postcondition: b = a
> // bn = an and bd = ad
>
> // comparison operator
> bool are_equal( rational a, rational b);
> // precondition: rational numbers a and b are sent in
> // postcondition: returns true if a = b else returns false
> // a = b iff an*bd = ad*bn
>
> // add rational numbers
> rational add( rational a, rational b );
> // precondition: send in rational numbers a,b where
> // b != 0
> // postcondition: calculate c = a + b by:
> // a = an/ad b = bn/bd
> // cn = an*bd + ad*bn
> // cd = ad*bd
> // reduce to lowest terms
> // subtract
> rational subt(rational, rational b);
>
> // multiply rationals
> rational mult( rational a, rational b);
> // precondition: b != 0
> // postcondition: calculate c = a*b by:
> // cn = an * bn
> // cd = ad * bd
> // reduce to lowest terms
>
> // divide rationals
> rational div(rational a, rational b);
> // precondition: b !=0
> // postcondition: calculate c = a/b by:
> // cn = an * bd
> // cd = ad * bn
> // reduce to lowest terms
>
>
>
>
//===============================IMPLEMENTATION=============================
===
> rational::rational()
> {
> my_numerator = 0;
> my_denominator = 0;
> }
> void rational::enter()
> {
> cout<< "A rational (numerator first)= " << "\n" << "\n";
> cin>> my_numerator;
> cin>> my_denominator;
> cout<< "\n";
> }
> void rational::change_numerator(int n)
> {
> my_numerator = n;
> }
> void rational::change_denominator(int d)
> {
> my_denominator = d;
> }
> int rational::get_numerator()
> {
> return (my_numerator);
> }
> int rational::get_denominator()
> {
> return (my_denominator);
> }
>
> rational::rational(int n, int d)
> {
> my_numerator = n;
> my_denominator = d;
> }
>
> //===============================CLIENT
> PROGRAM================================
>
> int main()
> {
> rational a,
> b,
> p,
> s,
> t,
> f;
> a.enter();
> b.enter();
> cout<< "\n";
> a.display();
> b.display();
> cout<< "\n" << "\n";
> cout<< "Sum= " << "\n";
> p.display();
> cout<< "Difference= " << "\n";
> s.display();
> cout<< "Product= " << "\n";
> t.display();
> cout<< "Quotient= " << "\n";
> f.display();
> }
>
> bool are_equal(rational a, rational b)
> {
> int an = a.get_numerator(),
> ad = a.get_denominator(),
> bn = b.get_numerator(),
> bd = b.get_denominator();
> if (an * bd == ad * bn)
> return( true );
> else
> return( false );
> }
>
> rational add(rational a, rational b)
> {
> int an = a.get_numerator(),
> ad = a.get_denominator(),
> bn = b.get_numerator(),
> bd = b.get_denominator(),
> pn = an * bd + bn * ad,
> pd = ad * bd;
> rational p(pn, pd);
> return p;
> }
>
> rational subt(rational a, rational b)
> {
> int an = a.get_numerator(),
> ad = a.get_denominator(),
> bn = b.get_numerator(),
> bd = b.get_denominator(),
> sn = an * bd - bn * ad,
> sd = ad * bd;
> rational s(sn, sd);
> return s;
> }
>
> rational mult(rational a, rational b)
> {
> int an = a.get_numerator(),
> ad = a.get_denominator(),
> bn = b.get_numerator(),
> bd = b.get_denominator(),
> tn = an * bn,
> td = ad * bd;
> rational t(tn, td);
> return t;
> }
>
> rational div(rational a, rational b)
> {
> int an = a.get_numerator(),
> ad = a.get_denominator(),
> bn = b.get_denominator(),
> bd = b.get_numerator(),
> fn = an * bn,
> fd = ad * bd;
> rational f(fn, fd);
> return f;
> }
>
> void rational::reduce(int pn, int pd, int sn, int sd, int tn, int td, int
> fn, int fd)
> {
> int j, d;
> if( pd >= pn)
> j = pn;
> else
> j = pd;
> for( d = j; d>0; d--)
> {
> if( pn%d ==0 && pd%d ==0)
> {
> pn = pn/d;
> pd = pd/d;
> }
> }
> if( sd >= sn)
> j = sn;
> else
> j = sd;
> for( d = j; d>0; d--)
> {
> if( sn%d ==0 && sd%d ==0)
> {
> sn = sn/d;
> sd = sd/d;
> }
> }
> if( td >= tn)
> j = tn;
> else
> j = td;
> for( d = j; d>0; d--)
> {
> if( tn%d ==0 && td%d ==0)
> {
> tn = tn/d;
> td = td/d;
> }
> }
> if( fd >= fn)
> j = fn;
> else
> j = fd;
> for( d = j; d>0; d--)
> {
> if( fn%d ==0 && fd%d ==0)
> {
> fn = fn/d;
> fd = fd/d;
> }
> }
> }
>
> void rational::display()
> {
> cout<< my_numerator << "/" << my_denominator << "\n";
> system("PAUSE");
> }
>
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