template keyword

template keyword

Declares a template, specialization, or instantiation

---

  declaration  :=  template-decl   explicit-instantiation   explicit-specialization   template-decl  ::= [export] template <  template-parm-list  >  declaration   template-parm-list  ::=  template-parm   template-parm-list  ,  template-parm   template-parm  ::=  type-parm   parm-decl   type-parm  ::= class [  identifier  ] [=  type-id  ]  typename [  identifier  ] [=  type-id  ]       template <  template-parm-list  > class [  identifier  ] [=  id-expr  ]  template-id  ::=  template-name  < [  template-arg-list  ] >  typename-name  ::=  identifier   template-arg-list  ::=  template-arg   template-arg-list  ,  template-arg   template-arg  ::=  assignment-expr   type-id   id-expr   explicit-instantiation  ::= template  declaration   explicit-specialization  ::= template < >  declaration   elaborated-type-specifier  :=  class-key  [::] [  nested-name  ::] [template]  template-id  typename [::]  nested-name  :: [template]  template-id   simple-type-specifier  := [::]  nested-name  :: template  template-id   postfix-expr  :=  postfix-expr  . [template]  id-expr   postfix-expr  -> [template]  id-expr   pseudo-dtor-name  := [::]  nested-name  :: template  template-id  :: ~  class-name   nested-name  :=  nested-name  [:: template  class-name  ]  qualified-id  := [::]  nested-name  :: [template]  unqualified-id  

The template keyword declares a template, a specialization of a template, or an instance of a template. The declaration can be a function declaration, function definition, class declaration, or class definition.

A template instance provides arguments for the template parameters, enclosing the arguments in angle brackets ( <> ). If the template is a member of a class, and the . or -> operator is used to access the member template, you must use the template keyword to tell the compiler to interpret the < symbol as the start of the template arguments. Similarly, use the template keyword in a qualified name when the name is used to instantiate the template in a context in which the compiler would interpret the < symbol as the less-than operator.

Example

  template  <typename T> T min(const T& a, const T& b) { return a < b ? a : b; } typedef complex<float> cfloat;  template  <> min<cfloat>(const cfloat& a, const cfloat& b) {   return cfloat(min(a.real(), b.real(  )), min(a.imag(), b.imag(  ))); }  template  int min<int>(const int&, const int&); 

See Also

class , expression , identifier , type , Chapter 7