Use visually distinct identifiers to eliminate errors resulting from misrecognizing the spelling of an identifier during the development and review of code. Depending on the fonts used, certain characters are visually similar or even identical:
- '1' (one) and 'l' (lower case el)
- '0' (zero) and 'O' (capital o)
Do not define multiple identifiers that vary only with respect to one or more visually similar characters.
When using long identifiers, try to make the initial portions of the identifiers unique for easier recognition. This also helps prevent errors resulting from non-unique identifiers (DCL32-C. Guarantee identifiers are unique).
Risk Analysis
Failing to use visually distinct identifiers can result in the wrong variable being used, causing unexpected program flow.
Recommendation |
Severity |
Likelihood |
Remediation Cost |
Priority |
Level |
|---|---|---|---|---|---|
DCL02-A |
1 (low) |
1 (unlikely) |
2 (medium) |
P2 |
L3 |
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
References
[[ISO/IEC 9899-1999]] Section 5.2.4.1, "Translation limits"
[[MISRA 04]] Rule 5.1