Why the result of the sum variable = 1?

Question

The output always equals to 1 and the mathimatical equation can't be completed

for (int i = 1; i <= x; i += 2) {
        sum += 1 / i;
    }

I expected the output of sum equals 4/3 when x equals 3 ,but the actual output is 1.

Answer 1

In languages like C, C++, and Java, dividing two integers rounds towards zero. So if I have:

int x = 3 / 5;

Then x == 0 because it rounded towards 0. Fixing this is pretty simple - just use a double instead of an int:

double sum = 0.0;
for(int i = 0; i <= x; i += 2) {
   sum += 1.0 / i; // 1.0 is a double, so division works as intended
}