[metadata]
id = "FLP30-C"
type = "rule"
category = "FLP"
number = 30
title = "Do not use floating-point variables as loop counters"
description = """
Because floating-point numbers represent real numbers, it is often mistakenly
assumed that they can represent any simple fraction exactly. Floating-point
numbers are subject to representational limitations just as integers are, and
binary floating-point numbers cannot represent all real numbers exactly, even if
they can be represented in a small number of decimal digits.
In addition, because floating-point numbers can represent large values, it is
often mistakenly assumed that they can represent all significant digits of those
values. To gain a large dynamic range, floating-point numbers maintain a fixed
number of precision bits (also called the significand) and an exponent, which
limit the number of significant digits they can represent.
Different implementations have different precision limitations, and to keep code
portable, floating-point variables must not be used as the loop induction
variable. See Goldberg's work for an introduction to this topic [Goldberg 1991].
"""
severity = "Low"
likelihood = "Probable"
priority = "P6"
level = "L2"
cert_version = "2016 Edition (Wiki)"
last_modified = "May 05, 2025"
[rules.cert_c.FLP30-C]
enabled = true
[references]
wiki = "https://wiki.sei.cmu.edu/confluence/display/c/FLP30-C.+Do+not+use+floating-point+variables+as+loop+counters"
cwe = []