cpp/regex/regex traits/transform

Obtains the sort key for the character sequence, such that if a sort key compares less than another sort key with , then the character sequence that produced the first sort key comes before the character sequence that produced the second sort key, in the currently imbued locale's collation order.

For example, when the regex flag std is set, then the sequence would match some character  if. Note that this function takes a character sequence as the argument to accommodate to the ranges defined like.

Standard library specializations of std return for some temporary string  constructed as.

Return value
The collation key for the character sequence in the currently imbued locale.