Why code using local struct as parameter for STL function does not compile in g++?

Question

I have such code which works well:

#include 
#include 

char x[11]= \"ABCDEFGHIJ\";
char y[11];

struct F {
    char operator ()         


        

Answer 1

g++ 4.5.1 compiles your code (with -std=c++0x option).

Your second code sample is ill-formed in C++03¹ but valid in C++0x

std::transform is

template < class InputIterator, class OutputIterator, class UnaryOperator >
  OutputIterator transform ( InputIterator first1, InputIterator last1,
                             OutputIterator result, UnaryOperator op );

However g++ 4.4 doesn't support local types as template arguments (even with -std=c++0x option] so you get an error.

_{1 : A local type, a type with no linkage, an unnamed type or a type compounded from any of these types shall not be used as a template-argument for a template type-parameter. (ISO C++03 §14.3.1.2)}