Fold expression

As explained in Learn C++ by Example

A fold expression is a C++ expression that applies an operator across the elements of a parameter pack.

How Learn C++ by Example covers it

How deep it goes

Explains pack declaration, function parameters, operators, association, and empty-pack initialization, but does not detail every fold form.

Examples

Demonstrates integer sums, subtraction, empty calls, string concatenation, and left- versus right-associative grouping.

What it assumes

Assumes parameter-pack syntax while explaining pack declarations, function tails, and compiler-deduced return types.

What you can do after

Apply it via C++17 fold syntax to replace recursive parameter-pack unpacking with concise variadic operations.

How it connects

Connects parameter packs, variadic templates, template argument deduction, recursion, and operator associativity.

liveBookmanning.com

Read Learn C++ by Example on liveBook Get the book at manning.com

Related concepts

• parameter packuses · A parameter pack is a C++ template or function parameter construct representing zero or more arguments, potentially of varying types.
• unary foldincludes · A unary fold is a fold expression that combines a parameter pack with an operator without an explicit initial value.
• variadic templatealternative to · A variadic template is a C++ template that uses a parameter pack to accept a variable number of template arguments.

This explainer was generated by Manning's knowledge graph from the text of Learn C++ by Example. The section links point to the parts of the book it draws on.