双重分裂一直给我“ INF”

Question

I have a function which the return type is double.

my return statement is

return sum / (double)(weight/100);

where sum is a double and weight is a int. I wrote printf statements before the return to check the values sum was 25.000 and (double)(weight/100) gave me .500
but the return statement gave me "inf"

what is wrong with it ?

Answer 1

You are doing integer division between weight and 100. How about:

return 100 * sum / weight;

With this way you multiply 100 and sum and you get a double again since sum is double. Then you divide the double result with the integer weight and you don't face the problem of integer division.

Answer 2

It looks like weight is probably an integer, so weight/100 gives 0 , and sum / 0.0 gives inf . Just rewrite it as:

return sum / (weight/100.0);

Answer 3

You have to cast the weight first to double. Now it divides an int by 100 to a new int. (Which probably becomes 0) Then you cast it to a double and then you divide sum by this answers. I would change it to:

return sum / ((double)weight)/100;