Struct HELP!

[-Beginners]

im learning by my own how to code with C++, i got to the topic of Structures. The book has some exercises and i am atempting to complete them..

it asks for a program that would be able to add fractions..
i have somehow an idea of how it would be, but my here's my problem.

I ask for the fraction, i would like to have that fraction compared to a variable thus making it decimal, so i can perform any operation (+, -, x, /) with decimals, and if possible that most common fractions be displayed (1/2, 1/4, 1/8) but not like1/3453.

here's the code of what i been working..
__________________________________________________ __


#include <iostream>
using namespace std;
struct math //structure tag
{

float firstInteger;

};
void main()
{
float equivalent;
math fraction; //define the structure object

cout<<"Enter the first integer: ";
cin>>fraction.firstInteger;



if (fraction.firstInteger= 1/2)
equivalent=.5;
cout<<"___this is the equivalent" <<equivalent<<endl;


cout<<"Your 1st Integer is: \n["<<fraction.firstInteger<<" ]"<<endl;

//End of code
_______________________________________________

any help would be appreciated, THANK YOU!

[kuphryn]

The logic looks correct. The problem has to do with I/O. One solution is to rend and entire line using std::getline() and a string object. Afterward, parse the input string accordingly.

Kuphryn

[Lynux-Penguin]

for programming fractions try something like this:

struct fraction
{
	int num;
	int den;
};

and work from there.

and for parsing user input... (a very crude method

char buf[256];
char num[256];
char den[256];
int j=0;
cin.getline(buf);
while(buf[j]!='/'&&j<strlen(buf))
{
	strcat(num,buf[j]);
	j++;
}
j++;
while(buf[j]!='\0'&&j<strlen(buf))
{
	strcat(den,buf[j]);
	j++;
}

and then convert char num[] and den[] to the string.

At least this is a rough idea... I'm sure there are better methods.


-LC

[beginnerss]

Can you be more specific with the

struct fraction
{
int num;
int den;
};


is there a function that can compare the string with a variable

if fraction == 1/2
then
half =0.5

half = fraction

[ygfperson]

//edit:
istringstream in("3/4");
in >> num >> den;

This doesn't check for a "/", but that requires more sophisticated code.

//edit2:
To check to see if fractions equal, the easiest way is to
1) convert a fraction to num and den
2) divide the two and store the result in a float or double. (cast num or den to a float or double.)
3) compare the double or float with another one

[Placid]

I'm working on representing fractions as well, but it seems that doing it with classes is easier, then you can overload the input (std::cin) function, and it works quite smoothly...

But when you want to learn structures:

struct fraction
{
    int num; // numerator
    int denom; // denominator
};

Basically, this declears the struct fraction to contain these two integers.

Then make some function to compare/add/multiply/divide two structures, something like this:

bool compareFractions( fraction& firstFraction, fraction& secondFraction )
{
    if( firstFraction.denom == secondFraction.denom )
        if( firstFraction.num == secondFraction.num)
            return true;
            // They are totally equal!
        else
            return false;
    else
        // Multiply up to the common denominator
        // Then compare the numerator
}

As you can see, compareFractions takes two fraction references and compares them.

As far as input is concerned, I have no idea of a good solution to that, other than creating classes, as I mentioned.

Hope some o' this helped

-- Placid

[laasunde]

This is wrong,

if (fraction.firstInteger= 1/2)

use == when comparing and = when assigning values to variables.