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• All simple fractions exactly.
• All decimals precisely, even when the decimals can be represented in a small number of digits.
• All digits of large values, meaning that incrementing a large floating-point value might not change that value within the available precision.

For the purpose of this rule, a loop counter is an induction variable that is used as an operand of a comparison expression that is used as the controlling expression of a do, while or for loop. An induction variable is a variable that gets increased or decreased by a fixed amount on every iteration of a loop [Aho 1986]. Furthermore, the change to the variable must occur directly in the loop body (rather than inside a function executed within the loop.)

This rule is a subset of NUM04-J. Do not use floating-point numbers if precise computation is required.

Noncompliant Code Example

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Bibliography

[Aho 1986]
[Bloch 2005]	Puzzle 34, "Down for the Count"
[JLS 2015]	§4.2.3, "Floating-Point Types, Formats, and Values"
[Seacord 2015]	NUM09-J. Do not use floating-point variables as loop counters LiveLesson

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