Simplest way to calculate amount of even numbers in given range

Question

What is the simplest way to calculate the amount of even numbers in a range of unsigned integers?

An example: if range is [0...4] then the answer is 3 (0,2,4)

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Answer 1

The range is always [2a+b, 2c+d] with b,d = {0,1}. Make a table:

b d | #even
0 0 | c-a+1
0 1 | c-a+1
1 0 | c-a
1 1 | c-a+1

Now a = min/2, b = min % 2, c = max/2 and d = max % 2.

So int nEven = max/2 - min/2 + 1 - (min%2).