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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
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  • Bug76
  • Security Hotspot19
  • Code Smell207

  • Quick Fix 19
Filtered: 7 rules found
unpredictable
    Impact
      Clean code attribute
        1. Arguments evaluation order should not be relied on

           Bug
        2. Keywords shall not be used as macros identifiers

           Code Smell
        3. Dereferenced null pointers should not be bound to references

           Code Smell
        4. Header guards should be followed by a matching "#define" macro

           Code Smell
        5. "memcmp" should only be called with pointers to trivially copyable types with no padding

           Bug
        6. Stack allocated memory and non-owned memory should not be freed

           Bug
        7. The "<stdlib.h>" functions "bsearch" and "qsort" should not be used

           Bug

        Header guards should be followed by a matching "#define" macro

        intentionality - logical
        maintainability
        Code Smell
        • unpredictable

        Why is this an issue?

        More Info

        Using include guards, wrapping around the entire content of a header file, is a best practice ensuring that no matter how many times the header is included in a translation unit, its content will only be seen once. 

        The include guard pattern is made up of four parts:

        • #ifndef at the top of the file, with a unique macro name (usually, the name relates to the file’s name to ensure uniqueness).
        • #define with the same macro name.
        • The content of the file
        • #endif at the end of the file

        The rule raises an issue when the name in the second part differs from the first (usually because of a typo or a copy/paste issue).

        Because the include guard pattern is cumbersome, virtually every compiler provides a non-standard alternative: #pragma once. This directive prevents multiple inclusions of the file that contains it without needing to invent a unique macro name for each file. Note that it relies on the notion of same file, which can be tricky to determine. Additionally, it will not work with build systems that copy headers in different places.

        Noncompliant code example

        #ifndef MYFILE_H
        #define MY_FILE_H // Noncompliant
        //...
        #endif
        

        Compliant solution

        The most straightforward way is to make both macro names match:

        #ifndef MYFILE_H
        #define MYFILE_H
        //...
        #endif
        

        An alternative is to use #pragma once instead:

        #pragma once
        //...
        
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          Developer Edition
          Available Since
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