Here's another (simplified) program I can't get to work.
I'm trying to write a generic routine that finds the largest element of a
sequence.
It is assumed that element->size() is defined, as it is for boost::array and
std::string.
For some reason, the Largest template function works okay for std::strings,
but not for boost::arrays.
Can you tell me what is wrong?
Will you please offer some improvements for error detection and debugging
techniques that would have helped here?
Perhaps I need a "typename" or "template" somewhere.
Take it as given that I have a String class that needs to be a fixed-size
array.
Here's the code:
#include
#include
#include
#include
#include
#include
#include
#include
#include <cstddef>
#include <iterator>
#include <algorithm>
#include <functional>
#include <string>
#include <vector>
#include <iostream>
#include <iomanip>
template <class InIter>
InIter Largest(InIter first, InIter last) {
typedef typename boost::pointee<InIter>::type ObjType;
InIter largest = std::max_element(first, last,
boost::bind(std::lessstd::size_t(),
boost::bind(&ObjType::size, _1),
boost::bind(&ObjType::size, _2))
);
return largest;
} // Largest
template
class String: public boost::array {
public:
std::string str() const {
if (this->back() == '\0')
return std::string(this->data());
return std::string(this->data(), this->size());
} // str
String() { this->assign('\0'); }
String(const std::string& str_) {
if (str_.size() > this->size())
throw std::runtime_error("String::ctor: str_ too big");
int copied = str_.copy(this->c_array(), this->size());
std::fill_n(this->begin() + copied, this->size() - copied, '\0');
} // ctor
operator std::string() const { return str(); }
}; // String
using namespace std;
int main(int argc, const char* argv[]) {
// typedef String<64> ArgStr; // <-- This won't compile.
typedef string ArgStr; // <-- This compiles/runs ok.
vector<ArgStr> args;
while (--argc)
args.push_back(string(*++argv));
if (args.empty()) {
cout << "no args!" << endl;
return EXIT_FAILURE;
}
cout << "args=";
copy(args.begin(), args.end(), ostream_iterator<string>(cout, " "));
cout << endl;
vector<ArgStr>::iterator iter = Largest(args.begin(), args.end());
cout << "Largest arg is '" << string(*iter) << "'." << endl;
return EXIT_SUCCESS;
} // main
