66 lines
2.6 KiB
Plaintext
66 lines
2.6 KiB
Plaintext
== Why is this an issue?
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Non-encoded https://en.wikipedia.org/wiki/Control_character[control characters] and whitespace characters are often injected in the source code because of a bad manipulation. They are either invisible or difficult to recognize, which can result in bugs when the string is not what the developer expects. If you actually need to use a control character use their encoded version:
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* https://en.wikipedia.org/wiki/ASCII[ASCII], for example `\n` and `\t`
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* https://en.wikipedia.org/wiki/Unicode[Unicode], for example `U+000D` and `U+0009`
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This rule raises an issue when the following characters are seen in a https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/[string literal]:
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* https://en.wikipedia.org/wiki/ASCII#Control_characters[ASCII control character]. (character index < 32 or ++=++ 127)
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* Unicode https://en.wikipedia.org/wiki/Unicode_character_property#Whitespace[whitespace characters].
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* Unicode https://en.wikipedia.org/wiki/C0_and_C1_control_codes[C0 control characters]
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* Unicode characters ``++U+200B, U+200C, U+200D, U+2060, U+FEFF, U+2028, U+2029++``
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=== Exceptions
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* https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/#verbatim-string-literals[Verbatim string literals] and https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/#raw-string-literals[raw string literals], since they have no escape mechanism
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* The simple space character: Unicode `U+0020`, ASCII 32
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== How to fix it
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=== Code examples
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==== Noncompliant code example
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[source,csharp,diff-id=1,diff-type=noncompliant]
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----
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string tabInside = "A B"; // Noncompliant: contains a tabulation
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string zeroWidthSpaceInside = "foobar"; // Noncompliant: contains a U+200B character inside
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Console.WriteLine(zeroWidthSpaceInside); // Prints "foo?bar"
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----
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==== Compliant solution
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[source,csharp,diff-id=1,diff-type=compliant]
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----
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string tabInside = "A\tB"; // Compliant: escaped value
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string zeroWidthSpaceInside = "foo\u200Bbar"; // Compliant: escaped value
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Console.WriteLine(zeroWidthSpaceInside); // Prints "foo?bar"
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----
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== Resources
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=== Documentation
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* https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/strings/[Strings and string literals]
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* https://en.wikipedia.org/wiki/Control_character[Control character]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Replace the control character at position XX by its escape sequence 'XX'.
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'''
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== Comments And Links
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(visible only on this page)
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include::../comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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