cpp/ranges/ssize

Returns the size of a range converted to a signed type.

If is well-formed, a call to  is expression-equivalent to, where  denotes
 * the corresponding signed version of, if it is wider than std, or
 * std otherwise.

If is ill-formed, a call to  is also ill-formed, which can result in substitution failure when  appears in the immediate context of a template instantiation.