Thread: Where's my program's problem? (Floating point exception?)

Hey guys, I've got the program to compile correctly, but every time I execute, it gives me the line says "Floating point exception"? Maybe my logic isn't correct or I code somewhere wrong?


*EDIT: Well, I see the problem is the denominator can't be zero, and I correct that...and it runs now...
But the output is not correct because it doesn't choose the smallest denomintor


The programming I'm trying to do is to let the user input a nonnegative real number,
and output a fraction the closest to the input, and print out the error also.
[Error is the difference between input and output]

The denominator has to be <= 100, and it also prints out the smallest denominator, like 0.751 are 3/4, 6/8,... 75/100, but it chooses 3/4 to print out...

For example: My input is 0.751 -> printout 3/4, error = -00.100
another example: input is 42.7488 -> printout 171/4, error = 0.00120

Here's my code:

Code:

#include <stdio.h>

int main() {
    
    //Define data types
    
    int d, n, num, lown, lowd;
    double dec, error_sq, sm_err=1, sm_err_sq;
    
    //Print this line on screen
    printf("Nonnegative real number: ");
    
    //Scan user input
    scanf("%d.%lf", &num, &dec);
    
    //Using for loop, create "d"inomirator and "n"umerator part
    //to find the closest approx.
    
    for(d=1; d<=100; d++){
             for(n=0; n<=100; n++){
                      
        
    //In order to compare the the error
    //I have to square them both too, to make it both in positive values
    //Then compare them two
                  
                      sm_err_sq = sm_err * sm_err;
                      
                      error_sq = (dec - n/d)*(dec - n/d);
                      
                      //Using IF condition to sort the smallest error each time looping
                      if (error_sq<sm_err_sq){
                                                lown = n;
                                                lowd = d;
                                                
                                                sm_err = dec - n/d;
                      }
             }
    }
                                  
    
    //Print the desire value
    
    printf("Closest approximation = %d/%d, Error = %lf\n", num*d+n, d, sm_err);
 
 
 
 
 return 0;   
}

Thanks for helping out. =]

error_sq = (dec - n/d)*(dec - n/d);

What happens on the first loop? d is set to 0...

Suggest using abs or fabs instead of square funtion.

abs - C/C++ Function Reference

http://www.cplusplus.com/reference/clibrary/cmath/fabs/


What do you think the value of 3/4 is? It returns an integer not a float.

Tim S.