Can You Pass `auto` as a Function Argument in C ?

Passing Auto as an Argument in C

Auto, introduced in C 11, serves as a placeholder type to deduce the actual type based on initialization. While typically used to infer the type of variables, it is also possible to pass auto as an argument to functions.

C 20 Allows Auto as Function Parameter Type

C 20 introduces support for using auto as a function parameter type. This enables functions to accept arguments of any type, allowing for greater flexibility and code reusability.

Consider the following example:

int function(auto data) {
    // Do something
}

In this code, the function function accepts an argument of type auto, which means it can accept arguments of any type. This allows the function to be used with different types of data without the need for multiple overloads.

Abbreviated Function Template

When used as a function parameter type, auto acts as an abbreviated function template. This means that the function can be used with arguments of different types, and the type of the argument will be deduced from the context.

Constrained Auto Parameters

While C 20 allows for unconstrained auto parameters, it also supports constrained auto parameters. Constrained auto parameters use concepts to specify constraints on the type of the argument. For example:

void function(const Sortable auto& data) {
    // Do something that requires data to be Sortable
}

In this code, the function function accepts an argument of type const Sortable auto&. This means that the argument must be a const reference to a type that satisfies the Sortable concept. This ensures that the function can only be used with types that meet specific requirements.

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