Re: [Boost-users] Getting Environment Variables

From: Angus Leeming (angus.leeming_at_[hidden])
Date: 2006-01-20 07:59:10

Sebastian Redl wrote:

> Aaron Griffin wrote:
> 
>>std::string get_env(std::string const& name)
>>{
>>   char* var = getenv(name.c_str());
>>   //getenv can return NULL, std::string(NULL) throws
>>   if(var) return var;
>>   else return "";
>>}
>>  
>>
> An empty environment variable is not exactly the same as a non-existent
> one. Perhaps like this:
> boost::optional<std::string> get_env(std::string const &name)
> {
>   char *var = getenv(name.c_str());
>   if(var) return var;
>   else return boost::nothing;
> }

Here's some GPL-ed code to set and get environment variables that works on
both *nix and Windows:

http://www.lyx.org/cgi-bin/viewcvs.cgi/lyx-devel/src/support/environment.C?rev=HEAD&content-type=text/vnd.viewcvs-markup
Equivalent url: http://tinyurl.co.uk/o5jo

Of course, as Sebastian points out, boost::optional would be more
elegant/correct for the getenv wrapper.

HTH,
Angus