Re: template error with iterator
utab <umut.tabak@gmail.com> wrote in news:50129083-18fd-4099-9ba7-
586bb9df72e2@a23g2000hsc.googlegroups.com:
Dear all,
I was experimenting with a template taking two iterators for the range
of
a vector.(Perhaps, it is sth simple and I am missing it because it is
a
late hour.) I ran into problems in the compile phase , the code is
below:
#include <iostream>
#include <algorithm>
#include <stdexcept>
#include <vector>
using std::domain_error;
using std::sort;
using std::vector;
template <class T, class Ran>
T median(Ran b, Ran e)
{
You are passing in only Ran arguments, there is no way the compiler could
deduce the T template parameter.
typedef typename vector<T>::size_type vec_sz;
vec_sz size = (e-b)/sizeof(T);
if (size == 0)
throw domain_error("median of an empty vector");
sort(b, e);
vec_sz mid = size/2;
return size % 2 == 0 ? (b[mid] + b[mid-1]) / 2 : b[mid];
}
int main()
{
vector<double> vec;
for(int i=0;i!=10;++i)
vec.push_back(i);
std::cout << median(vec.begin(), vec.end()) << std::endl;
... so you have to specify it yourself:
std::cout << median<double>(vec.begin(), vec.end()) << std::endl;
... or throw away the redundant template parameter:
template <class Ran>
typename Ran::value_type median(Ran b, Ran e)
{
typedef typename vector<Ran::value_type>::size_type vec_sz;
vec_sz size = (e-b)/sizeof(Ran::value_type);
if (size == 0)
throw domain_error("median of an empty vector");
....
hth
Paavo