Re: A C2664 error
On 12=D4 21=C8=D5, =CF =CE=E74=CA=B123=B7=D6, Ondra Holub <ondra.ho...@p=
ost.cz> wrote:
zhx...@gmail.com napsal:
Here is a program, I want to change the way which a map use to order
elements.
struct sizemore
{
bool operator()(const wstring &s1,const wstring &s2)
{
return s1.size()>s2.size();
}
};
int dictinput(const char *filename,map<wstring,wstring> &mwdict())
{
...
}
int main()
{
map<wstring,wstring> mwdict(sizemore());
dictinput("filename",mwdict);
}
But I receive a message:
error C2664: 'dictinput' : cannot convert parameter 2 from
'std::map<_Kty,_Ty> (__cdecl *)(sizemore (__cdecl *)(void))' to
'std::map<_Kty,_Ty> &(__cdecl *)(void)'
I'm always puzzled with parameters of function.
Could some one give me some advices?
Thanks a lot.
You need to specify comparation as 3rd parameter of template std::map.
See example below:
#include <iostream>
#include <map>
#include <string>
template<typename T>
struct CmpBySize
{
bool operator()(const T& s1, const T& s2) const
{
return s1.size() < s2.size();
}
};
typedef
std::map<std::string, std::string, CmpBySize<std::string> >
MapStrStr;
int main()
{
MapStrStr m;
m["aaa"] = "3 x a";
m["bb"] = "2 x b";
m["z"] = "1 x z";
const MapStrStr::const_iterator end = m.end();
for (MapStrStr::const_iterator i = m.begin(); i != end; ++i)
{
std::cout << "m[\"" << i->first << "\"] = \"" << i->second <<
"\"\n";
}
}
I have try your advice,but now the erroer information is:
cannot convert parameter 2 from 'std::map<_Kty,_Ty,_Pr>' to
'std::map<_Kty,_Ty,_Pr> &(__cdecl *)(void)
Is here anything wrong about the parameter of the fuctiocn?
int dictinput(const char
*filename,map<wstring,wstring,sizemore<wstring>> &mwdict());
And I sent a map<wstring,wstring,sizemore<wstring> object for the 3rd
parameter.