Addition of fractions in C: Floating point exception

Question

I'm writing a little program working with fractions:

struct fraction
{
     int num;
     int den;
};

typedef struct fraction FRAC;

I use a least common multiple function to add two fractions (without simpilfying them afterwards):

FRAC *add (FRAC a, FRAC b)
{
    int l = lcm(a.den, b.den);
    FRAC *sum;
    sum = malloc(sizeof(FRAC));
    sum->den = l;
    int la = l/a.den;
    int lb = l/b.den;
    sum->num = a.num*la + b.num*lb;
    return sum;
}

Given an array of FRAC I want to calculate the sum with following function:

FRAC* fraction_sum (FRAC *a, unsigned int size)
{
    int i;
    FRAC* sum = malloc(sizeof(FRAC));
    sum->num = 0;
    sum->den = 0;

    for (i = 0; i < size; i++)
    {
        FRAC b = {sum->num, sum->den};
        sum = add(b,a[i]);
    }

    return sum;
}

However this expression

print(*fraction_sum(fractions, N));

returns the error

Floating point exception (core dumped)

Any ideas? Is there a more elegant way to do this?

Answer 1

看起来您正在被零除。

Answer 2

将初始化更改为

   sum->den = 1;

Answer 3

You are dividing by zero .

The first time u call function add, the parameter a has both its num and den equal to zero. This causes that exception you are getting later in this expression.

int la = l/a.den;

Initializing b.den to 1 should stop your program from crashing. But it may not produce the correct sum I'm afraid.