If a file with the same name as a standard header is placed in the search path for included source files, the behavior is undefined.
The following table from the C Standard, subclause 7.1.2 [ISO/IEC 9899:2011], lists these standard headers:
<complex<ctype<errno<fenv<float<complex.h> | <inttypes.h> | <setjmp.h> |
<iso646<limits<locale<math<setjmp<stdarg<stdbool<stddef<stdint<stdio<stdlib<string<stdint.h> | <tgmath.h> | <wctype.h> |
<fenv.h> |
<time<uchar<wchar<wctype Do not reuse standard header file names, system-specific header file names, or other header file names.
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In this noncompliant code example, the programmer chooses to use a local version of the standard library but does not make the change clear.:
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| bgColor | #FFcccc |
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| lang | #ffccccc |
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#include "stdio.h" /* confusingConfusing, distinct from <stdio.h> */
/* ... */
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The solution addresses the problem by giving the local library a unique name (as per guideline PRE08-C. Guarantee that header file names are unique), which makes it apparent that the library used is not the original.:
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| bgColor | #ccccFF |
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| lang | c#ccccff |
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/* Using a local version of stdio.h */
#include "mystdio.h"
/* ... */
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Using header file names that conflict with other header file names can result in an incorrect file being included.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
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PRE04-C |
low unlikely medium Automated Detection
| Tool | Version | Checker | Description |
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sectionc:c: Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
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Bibliography
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Bibliography
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PRE03-C. Prefer typedefs to defines for encoding types 01. Preprocessor (PRE) 
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