Rule 13.3 - Using ++/-- with a volatile variable in C

Rule 13.3 - Using ++/-- with a volatile variable in C - Printable Version

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Rule 13.3 - Using ++/-- with a volatile variable in C - bsmith23 - 06-02-2024

Hello,
I saw in a previous post (https://forum.misra.org.uk/showthread.php?tid=1302), it was discussed that

Code:
volatile int x = 0;

x++;

where x is declared as volatile is a violation of rule 13.3 and changing this to be

Code:
x += 1;

results in compliance with rule 13.3. Would someone be able to explain why this is the case?

RE: Rule 13.3 - Using ++/-- with a volatile variable in C - misra-c - 10-07-2025

Accessing a volatile has potential side effects, beyond the simple read operation - hence the violation of Rule 13.3.

x += 1 does not violate Rule 13.3, because that Rule explicitly only applies to ++ and --, and not to += or -=