Re: How to encode text into html format

Kai-Uwe Bux <>
Sun, 01 Jun 2008 17:01:47 -0400
James Kanze wrote:

On Jun 1, 8:11 pm, Kai-Uwe Bux <> wrote:

Fred Yu wrote:

I want to encode input text into html format such as replace "<" with
"&lt", replace "&" with "&amp".
Could you give me some ideas? Thanks.

Containers: std::map< char, std::string >
Iterators: std::istream_iterator, std::ostream_iterator
Algorithms: std::transform

Agreed for the first (although it may be overkill---in this
particular case, I think I'd go with a simple switch).

No real need for the second; just use istream::get() and
ostream::put() (or operator<< in some cases).

As to the third: how? You're replacing a single character with
a sequence of characters, and transform does a one to one (which
in practice makes it of fairly limited utility---although I've
used it with a vector<string>, ostream_iterator, and as string
transformer class that I've written, which works something like
$(patsubst...) in GNU make).

I was thinking of something like this:

#include <iostream>
#include <iterator>
#include <map>
#include <algorithm>
#include <cassert>

struct encoder {

  std::map< char, std::string > the_map;

  encoder ( void ) {
    the_map[ 'a' ] = "a";
    // ...
    the_map[ '&' ] = "&amp";
    // ...

  std::string const & operator() ( char ch ) const {
    std::map< char, std::string >::const_iterator iter =
      the_map.find( ch );
    assert( iter != the_map.end() );
    return ( iter->second );

int main ( void ) {
  encoder the_encoder;
  std::transform( std::istreambuf_iterator<char>( std::cin ),
                  std::ostream_iterator<std::string>( std::cout, "" ),
                  the_encoder );


Kai-Uwe Bux

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