error: no matching function for call to ‘ptr_fun()’

下面这段代码会报错:报错信息为error: no matching function for call to ‘ptr_fun(<unresolved overloaded function type>) 

#include <algorithm>

#include <cctype>
#include <string>

const std::string StrToUpper(std::string s)
{
  std::transform(s.begin(), s.end(), s.begin(),std::ptr_fun(std::toupper));
  return s;

}

 

Solution

 

Explicitly add the template parameters:

 

#include <algorithm> #include <cctype> #include <string> //From http://www.richelbilderbeek.nl/CppStrToUpper.htm const std::string StrToUpper(std::string s) {   std::transform(s.begin(), s.end(), s.begin(),std::ptr_fun<int,int>(std::toupper));   return s; }