Re: Instantiate a basic_string with a text value independent of char or wchar_t

From:
Victor Bazarov <v.bazarov@comcast.invalid>
Newsgroups:
comp.lang.c++
Date:
Tue, 18 Jun 2013 18:00:43 -0400
Message-ID:
<kpql0v$7q1$1@dont-email.me>
On 6/18/2013 5:33 PM, Ryan wrote:

I have a template method that extracts the file name from a string.

The string can either be a char or wchar_t type. I would like to define
the value "/\\" as the constructor value of my basic_string<T>. I'm
currently having to define the value "/\\" as a basic_string<char> and
using its iterators as an input for the basic_string<T>. Is it possible
to use "/\\" value directly in the basic_string<T>?

Ryan


Not sure what you're asking, would that work:

   template<class T> basic_string<T> getPattern();

   template<> basic_string<char> getPattern<char>()
   {
     return "/\\";
   }

   template<> basic_string<wchar_t> getPattern<wchar_t>()
   {
     return L"/\\";
   }

, and then use the one based on the T type:

    ...
        .find_last_of(getPattern<T>())

in your 'getFileName'? The proper one should be picked up. Or you
could simply overload it based on the 'T' itself:

    basic_string<char> getPattern(char) { return "/\\"; }
    basic_string<wchar_t> getPattern(wchar_t) { return L"/\\"; }

and use

    .find_last_of(getPattern(T(0)))

?

#include <string>
#include <iostream>

template<typename T>
std::basic_string<T> getFileName(
   std::basic_string<T> const& pathAndFileName) {
     std::basic_string<char> pattern("/\\");

     return pathAndFileName.substr(
       pathAndFileName.find_last_of(
         std::basic_string<T>(pattern.begin(), pattern.end())) + 1);
}

int main(int, char const *[]) {
   std::basic_string<char> string1("sub\\directory\\file.txt");
   std::string result1 = getFileName(string1);
   std::cout << result1 << std::endl;

   std::basic_string<wchar_t> string2(L"sub\\directory\\file.txt");
   std::basic_string<wchar_t> result2 = getFileName(string2);
   std::wcout << result2 << std::endl;

   return 0;
}


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