boost::algorithm::trim_if — Trim.
// In header: <boost/algorithm/string/trim.hpp> template<typename SequenceT, typename PredicateT> void trim_if(SequenceT & Input, PredicateT IsSpace);
Remove all leading and trailing spaces from the input. The supplied predicate is used to determine which characters are considered spaces. The input sequence is modified in-place.
Parameters:
Input
An input sequence
IsSpace
An unary predicate identifying spaces