CODEWITHSUNDEEP
c++arraysstruct
bryan
bryan

Reputation: 69

printing out elements of an array of structs

I can't seem to figure out what I am doing wrong ... I am writing a program to play the game quatro, which is a board game kind of like tic tac tow. In the game their are 16 unique pieces in which each piece has four "traits". (Tall or Short , Black or White , Hollow or Filled, Square or Circle)

I created a structure "pieces" in which "traits" is a member. I refer to traits as W for white, T for Tall, H or hollow ....

Anyway, I am just trying to create an array which holds all available pieces and displays them in a separate scaled down program. However I can't seem to print out the elements of the available array.

the error i am getting is

error: not match for 'operator <<' in std:cout << available[0]'

Here is what I am trying now ...

#include <iostream>
#include <iomanip>
#include <string>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <algorithm>

using namespace std;

struct Pieces{

string traits;

};

int main()
{
  Pieces p1;
p1.traits = "WSHR";

Pieces p2;
p2.traits = "BSHR";

Pieces p3;
p3.traits = "WTHR";

Pieces p4;
p4.traits = "BTHR";

Pieces available [4] = {p1.traits,p2.traits,p3.traits,p4.traits};

cout << available[0];


return 0;

}

I added a bunch of library's hoping that was the problem. When I dereference the available array ( &available[0] ) the address prints out but I can't seem to figure out how to print the value in the first slot of the array.

Any help would be greatly appreciated.

Upvotes: 1

Views: 5596

Answers (3)

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

error: not match for 'operator <<' in std:cout << available[0]'

You have to define a std::ostream& operator(std::ostream&, const Pieces&) operator to print out Pieces directly:

std::ostream& operator(std::ostream& os, const Pieces& pcs) {
    os << pcs.traits;
    return os;
}

Alternatively you can simply output the traits member from the struct Pieces directly:

std::cout << available[0].traits;

Upvotes: 1

axon
axon

Reputation: 1200

You should overload the '<<'operator (output stream operator), or output the 'traits' member. Also, you can use a custom constructor to make them easier to initialize, and even use the std::vector container:

#include <iostream>
#include <string>
#include <vector>

using namespace std;

struct Pieces{
    Pieces(){} // default c'tor
    Pieces(const string& t)
        : traits(t) {}

    string traits;

    friend ostream& operator<< (ostream& stream, const Pieces& p);
};

// overload the output stream operator for convenience
ostream& operator<< (ostream& stream, const Pieces& p)
{
    stream << p.traits;
    return stream;
}


int main()
{
    Pieces p1("WSHR");  // neater if you write a constructor overload that inits the contents
    Pieces p2("BSHR");
    Pieces p3("WTHR");
    Pieces p4("BTHR");

    Pieces available[4] = { p1, p2, p3, p4 };
    // Or you could init the elements directly in the array; 
    Pieces a2[1] = { Pieces("WSHR") };

    cout << available[0] << endl; 

    // This is my favorite way to declare and init the array
    vector<Pieces> avail = { Pieces("WSHR"), Pieces("BSHR"), Pieces("WTHR"), Pieces("BTHR") };
    cout << avail[0] << endl;
}

Upvotes: -1

Emil Laine
Emil Laine

Reputation: 42828

Because the array available contains objects of type Pieces, with cout << available[0] you're trying to pass a Pieces object to operator<< of std::cout.

But cout::operator<< is not overloaded for the type Pieces so it doesn't know what to do.

Either overload the operator<<[1] or simply output the string inside that struct:

cout << available[0].traits;

[1] See πάντα ῥεῖ's answer for an example.

Upvotes: 1

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