On Mon, 19 Jul 2004 13:49:47 +0200, jhonyxxx <jhonye@arrakis.es>
wrote:
[color=blue]
>I have the next programa in C++:[/color]
[snipped]
[color=blue]
>If I use with a single list of int istīs ok but if the list containing
>list<person> and I try generate the items with
>persona ficha;
>strcpy(ficha.nombre,"hola");
>ficha.edad=40;
>and then I try to see with
>
> for (i = x.begin(); i != x.end(); i++) {
> cout << i->nombre<<"--";
> cout <<i->edad<<"--";
> }
>
>the programa break down and tell to me that exists errors for
>compiling in the cout sentences, the exact message is :
>
>pointer to structure requeired on left side -> or ->*
>
>I have change al type of opertors over the iterators and I donīt
>solve the problem, what is wrong?[/color]
Did you use list<persona>::iterator?
[color=blue]
>Seems that I use list with atomic elements int, float char etc. all is
>ok but if the list is wit struct the iterator seems turn fool.
>help, me please thank you!![/color]
There are a lot of problems and errors in your code, here's a
corrected version:
#include <iostream> //no .h
#include <list> //no .h
#include <cstring> //c++ version
//cstdio not required
#include <ctime> //for time
#include <cstdlib> //for random functions
//"random" isn't a standard function. Here's a definition:
inline int random(int max)
{
return static_cast<int>(
static_cast<double>(std::rand()) * max / (RAND_MAX+1)
);
}
//typedef struct is not necessary in C++, it is a C "hack".
struct persona
{
char nombre[30];
int edad;
};
//to sort the list, need to define a < function.
bool operator<(persona const& lhs, persona const& rhs)
{
return strcmp(lhs.nombre, rhs.nombre) < 0;
}
int main ()
{
std::srand(static_cast<unsigned>(std::time(0)));
// Create a new, empty linked list of int.
std::list<persona> x;
// some random names to fill the list with.
char const* names[5] = {"hola", "hello", "foo", "bar", "baz"};
for (int t=1;t<=100;t++)
{
persona ficha;
std::strcpy(ficha.nombre,names[random(5)]);
ficha.edad=40;
x.push_back(ficha);
}
// Show all of the items now in the list.
std::list<persona>::iterator i;
for (i = x.begin(); i != x.end(); i++)
{
std::cout << i->nombre<<"--";
std::cout <<i->edad<<"--";
}
//no need to use printf
//mixing printf and cout can be dangerous (see
//std::ios_base::sync_with_stdio).
std::cout << "\n\n\n";
std::cout << x.size() << '\n';
std::cout << x.max_size() << '\n';
std::cout << "\n\n\n";
x.sort();
for (i = x.begin(); i != x.end(); i++)
{
std::cout << i->nombre<<"--";
std::cout <<i->edad<<"--";
}
//always a good idea to finish output with a \n
std::cout << '\n';
}
And here's a version using some improved C++ facilities:
#include <iostream> //no .h
#include <list> //no .h
#include <string> //c++ version
#include <algorithm>
#include <iterator>
//cstdio not required
#include <ctime> //for time
#include <cstdlib> //for random functions
//"random" isn't a standard function. Here's a definition:
inline int random(int max)
{
return static_cast<int>(
static_cast<double>(std::rand()) * max / (RAND_MAX +
1)
);
}
//typedef struct is not necessary in C++, it is a C "hack".
struct persona
{
//added a constructor to initialize the persona
persona(std::string nombre, int edad)
:nombre(nombre), edad(edad)
{
}
//crucially nombre can now be any length.
std::string nombre;
int edad;
};
//to sort the list, need to define a < function.
bool operator<(persona const& lhs, persona const& rhs)
{
return lhs.nombre < rhs.nombre;
}
//add output streaming support to persona.
std::ostream& operator<<(std::ostream& os, persona const& p)
{
os << '(' << p.nombre << ", ";
os << p.edad << ')';
return os;
}
//define a random person generator.
struct persona_gen
{
static char const* names[5];
persona operator()() const
{
return persona(names[random(5)], random(40));
}
};
char const* persona_gen::names[5] = {"hola", "hello", "foo", "bar",
"baz"};
int main ()
{
//seed the random number generator with the current time.
std::srand(static_cast<unsigned>(std::time(0)));
// Create a new, empty linked list of persona.
std::list<persona> x;
// add 100 random entries.
std::generate_n(std::back_inserter(x), 100, persona_gen());
// Show all of the items now in the list.
std::copy(
x.begin(),
x.end(),
std::ostream_iterator<persona>(std::cout, "--")
);
std::cout << "\n\n\n";
std::cout << x.size() << '\n';
std::cout << x.max_size() << '\n';
std::cout << "\n\n\n";
x.sort();
std::copy(
x.begin(),
x.end(),
std::ostream_iterator<persona>(std::cout, "--")
);
//always a good idea to finish output with a \n
std::cout << '\n';
}
Tom
Problems with iterators ans lists 
