#include <iostream>
#include <cstring>

char* strdupn(const char* s)
{
	size_t len = strlen(s);
	char* dup = new char[len + 1];
	strcpy(dup, s);
	return dup;
}

char* f(char* s)
{
	for (char* p = s; *p; ++p)
		if ( *p >= 'A' && *p <= 'Z')
			*p += 'a' - 'A';

	return s;
}

int main()
{
	char s[] = "¿Qué Hace Esto?";
	char* dups = strdupn(s);
	std::cout << f(dups) << " :: " << s << std::endl;
	delete [] dups;
	return 0;
}