Problem with reducing fraction program

[Turtal]

I have a program where it will take any fraction and reduce it if possible, but my only problem with it is prime numbers. If the user inputs something such as 11/7, it will return 2 + 1/7 instead of 2 + 3/7, or if 7/11 is entered, a big mess is just returned. Everything else works fine though. Not sure where to go from here. Here is my code so far.

#include <stdio.h>

int main (void)


    {
    int a, b, temp=0,m=0;  
    int gcd(int,int);
    int lcm(int,int);
    int whole, minus, top, bottom, top2, bottom2;
	

    printf ("Enter fraction: ");
    scanf ("&#37;d/%d",&a,&b);

    whole = a / b; 
    minus = a - (whole*b);
    top = lcm(a,b) / b;
    bottom = lcm(a,b) / gcd(a,b);

    if ((a-b<=0))


        {
        temp=a;
        a=b;
        b=temp;
    }

    if(whole == 0)  
        printf("result: %d/%d\n", top, bottom);

    while(whole != 0){ /
    if(a % b == 0) 
        printf("result: %d\n", whole);
        break;
        }

    if( a % b > 0 && a <= 9) /
        printf("result: %d + %d/%d\n", whole, minus, b);

        top2 = top / top;  
        bottom2 = bottom / top;

    if( a % b > 0 && a > 9) 
        printf("result: %d + %d/%d\n", whole, top2, bottom2);

    printf("PROGRAM ENDS\n");
    return 0;
}
int gcd(a,b)  


    {
    int t,r;
    r=a%b;
    if (r==0)
    return b;
    else
    return gcd(b,r);
}
int lcm(a,b) 


    {
    int m,n;
    m=a*b;
    n=m/gcd(a,b);
    return n;
}

[Elysia]

Don't put function prototypes inside main.
Work on your indenting too.

[Dino]

...but my only problem with it is prime numbers.

I don't think so.

1) You don't need the lcm() function to do the math you need to do.
2) You have WAY too many variables
3) You don't need to swap "a" and "b" before calling gcd().
4) Your code is poorly structured regardless of poor indentation.

Here are the steps you need to do:

1) check for a user supplied denominator of zero. Exit if supplied.
2) Figure out the whole portion - you got that.
3) If there is a remaining fraction, (not zero or 1), call gcd with the remaining fraction and the user supplied denominator. Then, reduce both of those values by the gcd.
4) print out the results.

Todd

[Dino]

P.S. After you gets yours working, I'll post mine.

Todd

[Turtal]

I finaly got it to work. I know it's messy and completely drawn out, but the only way I seemed to understand how to do this, is when I had a problem, I created more code to fix the problem rather than just fix what I have, = 0
hence the spagetti. It still has issues with prime numbers though, such as 7/11 etc, but I got it to work where if the numerator is larger than the denom, such as 11/7, it now works fine.

#include <stdio.h>

int main (void)

    {
    int a, b, temp=0,m=0;
    int gcd(int,int);
    int lcm(int,int);
    int whole, minus, top, bottom, top2, bottom2, newnom;
	

    printf ("Enter fraction: ");
    scanf ("&#37;d/%d",&a,&b);

    whole = a / b;
    minus = a - (whole*b);
    top = lcm(a,b) / b;
    bottom = lcm(a,b) / gcd(a,b);

    if ((a-b<=0))
    {
        temp=a;
        a=b;
        b=temp;
    }

    if(whole == 0)
        printf("result: %d/%d\n", top, bottom);

    while(whole != 0){ 
    if(a % b == 0) 
        printf("result: %d\n", whole);
        break;
        }

    if( a % b > 0 && a <= 9) 
        printf("result: %d + %d/%d\n", whole, minus, b);

        newnom = a % b; 
        top2 = newnom / gcd(a,b);
        bottom2 = bottom / top;

    if( a % b > 0 && a > 9) 
	
        printf("result: %d + %d/%d\n", whole, top2, bottom2);

    printf("PROGRAM ENDS\n");
    return 0;
}
int gcd(a,b)
{
    int t,r;
    r=a%b;
    if (r==0)
    return b;
    else
    return gcd(b,r);
}
int lcm(a,b)
{
    int m,n;
    m=a*b;
    n=m/gcd(a,b);
    return n;
}

[/CODE]

P.S. I took out the part where if the user entered zero, the program would ask them to enter a nonzero number, because it wasn't necessary and the compiler website my prof. used to grade the program didn't require it.

[Dino]

Behold... some beautifully simple, nicely indented, meaningful variable named code:

#include <stdio.h>

int gcd(int,int);

int main (void) {
	
	int numerator, denominator = 1 ; 
    int whole, portion , divisor = 1 ; 
	
    printf ("Enter fraction: ") ;
    scanf ( "&#37;d/%d" , &numerator, &denominator ) ;

	if (denominator == 0) { 
		printf("Invalid Denominator of 0\n") ; 
		return 8 ; 
	} 
	
    whole = numerator / denominator ; 
    portion = numerator - (whole * denominator);
	
	// reduce the fraction. 
	if (portion != 0 ) divisor = gcd(portion, denominator) ; 

	portion /= divisor ; 
	denominator /= divisor ; 

	printf("results: ") ; 
	if ( whole > 0) printf("%d ", whole); 
	if ( portion > 0) printf("%d/%d", portion, denominator ) ;
	else if (whole == 0) printf("0") ; 
	printf("\n") ; 
 
    printf("PROGRAM ENDS\n");
    return 0;
}

int gcd(a,b)  {
    int r ;  // Remainder
	r= a % b ;
    if (r==0) return b;
    else return gcd(b,r);
}

Todd

(EDIT: forum software - so much for my well indented code...)

[Turtal]

Thanks for the help. I'm going to clean mine up and resubmit it.

[Dino]

The big question is: Do you understand the differences?

[Turtal]

Now I do. I think I, and probly 99% of the world, learn off examples.

[Elysia]

(EDIT: forum software - so much for my well indented code...)

It's not wise to mix spaces and tabs. Use one, but not both. That will avoid the code messing up.
And function prototypes are not supposed to be inside functions! They're supposed to be in headers, or at the very least, at the beginning of your .c or .cpp file in case you don't have one.

[IceDane]

Your code doesn't have to be that long/complex.. Use some ternary and some division and modulo, and voila.. And yes, I like ternary.

#include <stdio.h>

int main(void)
{
     int nr1 = 0, nr2 = 0, i = 0, gcd = 0;
     
     
     printf("Enter a fraction(x/y): ");
     scanf("&#37;d%*c%d", &nr1, &nr2);

     if(!(nr1&&nr2)) return -1;
     
     if(nr2 % nr1 == 0) { nr2 /= nr1; nr1 = 1; }
     
     else
          for(i = 2; i <= ((nr1<nr2) ? (nr1/2) : (nr2/2) ); i++)
               gcd = ( !(nr1%i) && !(nr2%i) ) ? i : gcd;

     
     if(gcd != 0) { printf("GCD = %d\n", gcd);  nr1 /= gcd; nr2 /= gcd; }
    
     
     (nr1 > nr2) ? printf("%d ", nr1/nr2) : 0;
     
     (nr1%nr2) ? printf("%d/%d\n", nr1%nr2, nr2) : 0;
     
     return 0;
}

[iMalc]

IceDane you Sicko, that's horrible!

Your code doesn't have to be obfuscated AND inefficient.

[IceDane]

IceDane you Sicko, that's horrible!

Your code doesn't have to be obfuscated AND inefficient.

Haha.. Well, it looks nice IMO. =(

Anyway, is it the lack of nested if statements and extreme usage of modulus that makes it inefficient? Is modulus actually an inefficient operation?