Structured binding declaration (since C++17)
Binds the specified names to subobjects or elements of the initializer.
Like a reference, a structured binding is an alias to an existing object. Unlike a reference, a structured binding does not have to be of a reference type.
attr (optional) decl-specifier-seq ref-qualifier (optional) [ sb-identifier-list ] initializer ;
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| attr | - | sequence of any number of attributes | ||
| decl-specifier-seq | - | sequence of the following specifiers (following the rules of simple declaration):
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| ref-qualifier | - | either & or &&
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| sb-identifier-list | - | list of comma-separated identifiers introduced by this declaration, each identifier may be followed by an attribute specifier sequence(since C++26) | ||
| initializer | - | an initializer (see below) |
initializer may be one of the following:
= expression
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(1) | ||||||||
{ expression |
(2) | ||||||||
( expression )
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(3) | ||||||||
| expression | - | any expression (except unparenthesized comma expressions) |
A structured binding declaration introduces all identifiers in the sb-identifier-list as names in the surrounding scope and binds them to subobjects or elements of the object denoted by expression. The bindings so introduced are called structured bindings.
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One of the identifiers in the sb-identifier-list can be preceded by an ellipsis. Such an identifier introduces a structured binding pack. The identifier must declare a templated entity. |
(since C++26) |
A structured binding is an identifier in the sb-identifier-list that is not preceded by an ellipsis, or an element of a structured binding pack introduced in the same identifier list(since C++26).
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