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C

C static code analysis

Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code

  • All rules 315
  • Vulnerability13
  • Bug76
  • Security Hotspot19
  • Code Smell207

  • Quick Fix 19
Filtered: 22 rules found
confusing
    Impact
      Clean code attribute
        1. #include directives in a file should only be preceded by other preprocessor directives or comments

           Code Smell
        2. Loops should not have more than one "break" or "goto" statement

           Code Smell
        3. Switch labels should not be nested inside non-switch blocks

           Code Smell
        4. Appropriate char types should be used for character and integer values

           Code Smell
        5. The first element of an array should not be accessed implicitly

           Code Smell
        6. Multicharacter literals should not be used

           Code Smell
        7. GNU attributes should be used correctly

           Code Smell
        8. Functions which do not return should be declared as "noreturn"

           Code Smell
        9. Functions with "noreturn" attribute should not return

           Bug
        10. "else" statements should be clearly matched with an "if"

           Code Smell
        11. A conditionally executed single line should be denoted by indentation

           Code Smell
        12. Macros should not be redefined

           Code Smell
        13. "#include_next" should not be used

           Code Smell
        14. String literals should not be concatenated implicitly

           Code Smell
        15. Types and variables should be declared in separate statements

           Code Smell
        16. Format strings should be used correctly

           Code Smell
        17. Conditional operators should not be nested

           Code Smell
        18. Increment should not be used to set boolean variables to 'true'

           Code Smell
        19. Loops with at most one iteration should be refactored

           Bug
        20. Deprecated K&R syntax should not be used for function definition

           Code Smell
        21. Redundant pairs of parentheses should be removed

           Code Smell
        22. "/*" and "//" should not be used within comments

           Code Smell

        Format strings should be used correctly

        intentionality - logical
        maintainability
        Code Smell
        • cert
        • confusing

        Why is this an issue?

        More Info

        printf format strings contain placeholders, represented by special characters such as %s. These placeholders are interpreted at runtime rather than validated by the compiler. Using incorrect placeholders or with inappropriate arguments can result in the wrong string being created or undefined behavior.

        Starting with C++20, std::format should be preferred: it is more readable and validated at compile-time, making it more secure. Rule S6494 covers that. Furthermore, C++23 provides std::print, which is similar to std::format but directly prints its output instead of generating a std::string.

        S2275 covers errors leading to undefined behavior.
        This rule is about errors that produce an unexpected string.

        These problems are detected when the format string is a string literal:

        • Every argument should be used:
          printf("Numbers: %d", 1, 2); // Noncompliant: the second argument "2" is unused
          
          You should either remove the extra arguments or add the relevant placeholders.
        • The formatting flags 0 and - are mutually exclusive:
          printf("Number: %0-10f", 1.2); // Noncompliant: flag "0" is ignored because of "-"
          
          When 0 is used, the number is right-aligned with leading 0s. The flag - aligns the number to the left. Consequently, zero 0 would be used when using both flags, thus making the 0 flag useless. You should choose which flags make sense in your use case and remove the other.
        • The formatting flags ␣ (space) and + are mutually exclusive:
          printf("Number: % +f", 1.2); // Noncompliant: flag " " is ignored because of "+"
          
          Both the space and the + flags change when the sign character is printed. They are, therefore, incompatible with one another. You should decide which one is appropriate in your case and remove the other.
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