Lowercase letter l (ell) can easily be confused with the digit 1 (one). This can be particularly confusing when indicating that an integer literal constant is a long value. This recommendation is similar to DCL02-C. Use visually distinct identifiers.
Likewise, you should use uppercase LL rather than lowercase ll when indicating that an integer literal constant is a long long value.
Noncompliant Code Example
This noncompliant example highlights the result of adding an integer and a long value even though it appears that two integers 1111 are being added.
printf("Sum is %ld\n", 1111 + 111l);
Compliant Solution
The compliant solution improvises by using an uppercase L instead of lowercase l to disambiguate the visual appearance.
printf("Sum is %ld\n", 1111 + 111L);
Risk Assessment
Confusing a lowercase letter l (ell) with a digit 1 (one) when indicating that an integer denotation is a long value could lead to an incorrect value being written into code.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
DCL16-C | low | unlikely | low | P3 | L3 |
Automated Detection
Tool | Version | Checker | Description |
|---|---|---|---|
| 1.2 | ltrlsynt | Fully implemented | |
| PRQA QA-C | Unable to render {include} The included page could not be found. | Fully implemented |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
CERT C++ Secure Coding Standard: DCL16-CPP. Use 'L', not 'l', to indicate a long value
Bibliography
Lockheed Martin 2005 AV Rule 14, Literal suffixes shall use uppercase rather than lowercase letters.