What does the % operator do in Ruby in N % 2?

Question

if counter % 2 == 1 I am trying to decode this line - it\'s a Rails project and I am trying to figure out what the % does in this if statement.

Answer 1

To give a few ways to say it:

• Modulo operator
• Remainder operator
• Modular residue

Strictly speaking, if a % b = c, c is the unique constant such that

a == c (mod b) and 0 <= c < b

Where x == y (mod m) iff x - y = km for some constant k.

This is equivalent to the remainder. By some well known theorem, we have that a = bk + c for some constant k, where c is the remainder, which gives us a - c = bk, which obviously implies a == c (mod b).

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