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## Function template find_head

boost::algorithm::find_head — Find head algorithm.

## Synopsis

    // In header: <boost/algorithm/string/find.hpp>

    template<typename RangeT>
      iterator_range< typename range_iterator< RangeT >::type >
      find_head(RangeT & Input, int N);

## Description

Get the head of the input. Head is a prefix of the string of the given size. If the input is shorter then required, whole input if considered to be the head.

| Note
This function provides the strong exception-safety guarantee

Parameters: |
`Input` | An input string
`N` | Length of the head For N>=0, at most N characters are extracted. For N<0, size(Input)-|N| characters are extracted.
Returns: | An `iterator_range` delimiting the match. Returned iterator is either `Range1T::iterator` or `Range1T::const_iterator`, depending on the constness of the input parameter.