Re: Problems of template programming

From:
"Jim Langston" <tazmaster@rocketmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Thu, 30 Sep 2010 08:24:40 CST
Message-ID:
<i809c2$jl1$1@four.albasani.net>
"jungleman" <ustcrevolutionary@gmail.com> wrote in message
news:5ce02057-b929-4690-a416-04df4ee48d10@c13g2000vbr.googlegroups.com...

here's a template function:

template<typename _Tp>
double sum(const std::vector<_Tp>& data)
{
    ... ...
    ... ...
}

may it work? If not, How can I enable template functions like this?


First: your variable name _Tp is illegal in C or C++. Variables starting
with an underscore and followed by a capital letter are reserved for the
compiler. Tp_ would be legal however as would Tp.

Second: Did you try it? The following program outputs "5"

#include <vector>
#include <iostream>

template<typename Tp>
double sum(const std::vector<Tp>& data)
{
    // Some concern about the following line. User defined
    // classes/structures wouldn't be assignable to 0 like this.
   Tp total = 0;
   for ( auto i = data.begin(); i != data.end(); ++i )
      total += *i;
   return total;
}

int main(){
   std::vector<int> foo;
   foo.push_back( 2 );
   foo.push_back( 3 );
   std::cout << sum<int>( foo ) << std::endl;
}

Regards,

Jim Langston

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