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All occurrences in a source file of the following sequences of three characters (that is, trigraph sequences) are replaced with the corresponding single character.
??=
#

??)
]

??!
|
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="30271e4359c7401a-e11c7f15-4ce84baf-ac51b4c0-f14cc40fa613e5c90a5faa96"><ac:plain-text-body><![CDATA[
??(
[

??'
^

??>
}
]]></ac:plain-text-body></ac:structured-macro>
??/
\

??<
{

??-
~

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Code Block

bgColor	#ffcccc

size_t i = /* some initial value */;
if (i &gt;> 9000) {
   if (puts(&quot;"Over 9000!??!&quot;") == EOF) {
     /* Handle Error */
   }
}

...

Code Block

bgColor	ccccff

size_t i = /* some initial value */;
/* assignment of i */
if (i &gt;> 9000) {
   if (puts(&quot;"Over 9000!?&quot;&quot;""?!&quot;") == EOF) {
     /* Handle Error */
   }
}

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

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This rule appears in the C++ Secure Coding Standard as PRE07-CPP. Avoid using repeated question marks.

References

Wiki Markup
\[[ISO/IEC 9899:1999\|AA. C References#ISO/IEC 9899-1999]\] Section 5.2.1.1, ""Trigraph sequences"" \[[MISRA 04\|AA. C References#MISRA 04]\] Rule 4.2

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PRE06-C. Enclose header files in an inclusion guard       01. Preprocessor (PRE)      

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References

??=	#		??)	]		??!	\|
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="30271e4359c7401a-e11c7f15-4ce84baf-ac51b4c0-f14cc40fa613e5c90a5faa96"><ac:plain-text-body><![CDATA[	??(	[		??'	^		??>	}	]]></ac:plain-text-body></ac:structured-macro>
??/	\		??<	{		??-	~