DCL16-C. Use "L," not "l," to indicate a long value

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.

To be precise when using modifiers to indicate the type of an integer literal, the first character may not be l .  It may be L , u , or U . Subsequent characters have no strict case requirements.

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.

Automated Detection

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website .

Related Guidelines

Bibliography

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