Editing Sigil (computer programming) (section)

==Similar phenomena==
===Shell scripting variables===
In Unix [[shell scripting]] and in utilities such as [[Makefile]]s, the "<code>$</code>" is a unary operator that translates the name of a variable into its contents. While this may seem similar to a sigil, it is properly a [[unary operation|unary operator]] for lexical [[indirection]], similar to the <code>*</code> [[dereference operator]] for pointers in [[C (programming language)|C]], as noticeable from the fact that the dollar sign is omitted when assigning to a variable.

===Identifier conventions===
In [[Fortran language features|Fortran]], sigils are not used, but all variables starting with the letters I, J, K, L, M and N are [[integers]] by default. Fortran documentation refers to this as "implicit typing".  Explicit typing is also available to allow any variable to be declared with any type.

Various programming languages including [[Prolog]], [[Haskell (programming language)|Haskell]], [[Ruby (programming language)|Ruby]] and [[Go (programming language)|Go]] treat [[identifier]]s beginning with a capital letter differently from identifiers beginning with a small letter, a practice related to the use of sigils.

===Stropping===
{{main|Stropping (syntax)}}
Actually a form of [[stropping (syntax)|stropping]], the use of many languages in Microsoft's [[.NET Framework|.NET]] [[Common Language Infrastructure]] (CLI) requires a way to use variables in a different language that may be keywords in a calling language. This is sometimes done by prefixes. In [[C Sharp (programming language)|C#]], any variable names may be prefixed with "<code>@</code>". This is mainly used to allow the use of variable names that would otherwise conflict with keywords.<ref>{{cite web |url=http://msdn.microsoft.com/en-us/library/x53a06bb.aspx
|work=MSDN |title=C# Keywords |access-date=2011-03-23 }}</ref> The same is achieved in [[VB.Net]] by enclosing the name in square brackets, as in <code>[end]</code>.<ref>{{cite web
|url=http://msdn.microsoft.com/en-us/library/362314fe.aspx
|work=MSDN |title=string (C# Reference) |access-date=2011-03-23 }}</ref>

The "<code>@</code>" prefix can also be applied to string literals; see [[#Literal affixes|literal affixes]] below.

=== Hungarian notation ===
Related to sigils is [[Hungarian notation]], a [[Naming convention (programming)|naming convention]] for variables that specifies variable type by attaching certain alphabetic prefixes to the variable name. Unlike sigils, however, Hungarian notation provides no information to the compiler; as such, explicit types must be redundantly specified for the variables (unless using a language with [[type inference]]). As most standard compilers do not enforce use of the prefixes, this permits omission and also makes code prone to confusion due to accidental erroneous use.<ref name="Linux kernel coding style">[https://slurm.schedmd.com/coding_style.pdf Linux kernel coding style], by Linus Torvalds</ref>

===Literal affixes===
While sigils are applied to names (identifiers), similar prefixes and suffixes can be applied to [[Literal (computer programming)|literals]], notably [[integer literal]]s and [[string literal]]s, specifying either how the literal should be evaluated, or what data type it is. For example, <code>0x10ULL</code> evaluates to the value 16 as an unsigned long long integer in C++: the <code>0x</code> prefix indicates hexadecimal, while the suffix <code>ULL</code> indicates unsigned long long. Similarly, prefixes are often used to indicate a [[raw string]], such as <code>r"C:\Windows"</code> in Python, which represents the string with value <code>C:\Windows</code>; as an escaped string this would be written as <code>"C:\\Windows"</code>.

As this affects the semantics (value) of a literal, rather than the syntax or semantics of an identifier (name), this is neither stropping (identifier syntax) nor a sigil (identifier semantics), but it is syntactically similar.

===Java annotations===
Compare [[Java annotation]]s such as @Override and @Deprecated.

===Confusion===
In some cases the same syntax can be used for distinct purposes, which can cause confusion. For example, in [[C Sharp (programming language)|C#]], the "<code>@</code>" prefix can be used either for stropping (to allow reserved words to be used as identifiers), or as a prefix to a literal (to indicate a [[raw string]]); in this case neither use is a sigil, as it affects the syntax of identifiers or the semantics of literals, not the semantics of identifiers.