Is it possible to pass an array to a function?

Is it possible to pass an array to a function?

For example, I am trying to make a function called displaycards, which will display some cards, but I want it to display the cards from a deck which I have in an array in my “int main()” part of the program.

Yes.

Can you post the code related to your attempt?

Some thing like this...

Code:

---

#include <cstdlib>
#include <iostream>

using namespace std;

void displayCards();

int main(int argc, char *argv[])
{
    string Spade[13] = {"A", "2", "3", "4", "5" ,"6", "7", "8", "9", "10", "J", "Q", "K"};
    random_shuffle(Spade, Spade + 13);
       
    cout << "Player 1: \n";
    displayCards();
   
}

void displayCards()
{
    for (int i=0; i<=13; i++)
    { cout << "S: "; spade[i]); }
}

---

The function displayCards should receive arguments -- generally speaking, the start of the array and its size. And C and C++ are case sensitive.

Quote:

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Originally Posted by Dave_Sinkula

The function displayCards should receive arguments -- generally speaking, the start of the array and its size. And C and C++ are case sensitive.

---

Sorry you lost me?

basically, edit the function (and the prototype, of course) so that it takes two arguments: an array of type string, and an integer, to specify the length of the array.

hope it helps.

Quote:

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Originally Posted by nadroj

basically, edit the function (and the prototype, of course) so that it takes two arguments: an array of type string, and an integer, to specify the length of the array.

hope it helps.

---

something like this?

Code:

---

#include <cstdlib>
#include <iostream>

using namespace std;

void displayCards(string, int);

int main(int argc, char *argv[])
{
    string Spade[13] = {"A", "2", "3", "4", "5" ,"6", "7", "8", "9", "10", "J", "Q", "K"};
    random_shuffle(Spade, Spade + 13);
       
    cout << "Player 1: \n";
    displayCards(Spade, 13);
   
}

void displayCards(string Spade, int i)
{
    for (int i=0; i<=13; i++)
    cout << "S: "; Spade[i]);
}

---

almost.. with that code the function takes in a single string.. you want a string array.

Quote:

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Originally Posted by nadroj

almost.. with that code the function takes in a single string.. you want a string array.

---

Ok, so i have this.

Code:

---

void displayCards(string array, int);

int main(int argc, char *argv[])
{
    string Spade[13] = {"A", "2", "3", "4", "5" ,"6", "7", "8", "9", "10", "J", "Q", "K"};
    random_shuffle(Spade, Spade + 13);
       
    cout << "Player 1: \n";
    displayCards(Spade, 13);
   
}

void displayCards(string array Spade, int i)
{
    for (int i=0; i<=13; i++)
    cout << "S: "; Spade[i]);
}

---

but i get this error? " conversion from `std::string*' to non-scalar type `std::string' requested "

sorry if i am being a pain, i tried to look all this up on google, but that just confused me even more... lol

you know how to declare a string array, you did it in main! whats this 'array' keyword nonsense! :p

KISS! its no different!

edit: also, in your cout statement in the displayCards function remove the ')' and change the middle ';' to '<<'

Quote:

---

Originally Posted by nadroj

you know how to declare a string array, you did it in main! whats this 'array' keyword nonsense! :p

KISS! its no different!

edit: also, in your cout statement in the displayCards function remove the ')' and change the middle ';' to '<<'

---

ok, so so far i have this

Code:

---

#include <cstdlib>
#include <iostream>

using namespace std;

void displayCards(string Spade);

int main(int argc, char *argv[])
{
    string Spade[13] = {"A", "2", "3", "4", "5" ,"6", "7", "8", "9", "10", "J", "Q", "K"};
    random_shuffle(Spade, Spade + 13);
       
    cout << "Player 1: \n";
    displayCards(Spade[0,13]);
    system("pause");
    return EXIT_SUCCESS;
}

void displayCards(string Spade)
{
    for (int i=0; i<=13; i++)
    {
        cout << "S: " << Spade[i];
    }
}

---

it compiles fine, but when i run it i get this.

Quote:

---

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

---

ok, i think ive tortured you enough...

to declare your array of strings, you did:

Code:

---

string Spade[13]

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string[] is the datatype--that is, its a 'string array'. in your function and prototype, append '[]' to the datatype:

Code:

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void displayCards(string[] Spade);

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also, i would recommend using lower-case variable names (ie 'spade' not 'Spade') and camel-casing when necessary, as you have ('displayCards'). when i see a capital i think its a class name. my two cents.

Even

Code:

---

void displayCards(string Spade[13]);

---

would work. It's the same, you are declaring an array of strings, its just that this one is also a parameter to the function.

One other issue, you should be using < instead of <=. When i = 13, it is out of bounds of a 13 element array (valid indexes are 0 - 12).

Quote:

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Originally Posted by nadroj

ok, i think ive tortured you enough...

to declare your array of strings, you did:

Code:

---

string Spade[13]

---

string[] is the datatype--that is, its a 'string array'. in your function and prototype, append '[]' to the datatype:

Code:

---

void displayCards(string[] Spade);

---

also, i would recommend using lower-case variable names (ie 'spade' not 'Spade') and camel-casing when necessary, as you have ('displayCards'). when i see a capital i think its a class name. my two cents.

---

ok now i am really ripping my hair out!!!!

Code:

---

void displayCards(string[]);

int main(int argc, char *argv[])
{
    string spade[13] = {"A", "2", "3", "4", "5" ,"6", "7", "8", "9", "10", "J", "Q", "K"};
    random_shuffle(spade, spade + 13);
       
    cout << "Player 1: \n";
    displayCards(spade[0,13]);
    system("pause");
    return EXIT_SUCCESS;
}

void displayCards(string[13] spade)
{
    for (int i=0; i<13; i++)
        cout << "S: " << spade[i];
}

---

i get this message from the compiler

Quote:

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cannot convert `std::string' to `std::string*' for argument `1' to `void displayCards(std::string*)'

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You're making up syntax here.

What is this?

Code:

---

displayCards(spade[0,13]);

---

Should be this:

Code:

---

displayCards(spade);

---

You are supposed to pass the variable spade, not spade[0,13] (is that even valid syntax?).

I am getting a little confused by Java at the moment, but in C++ I would write it as:

Code:

---

void displayCards(string spade[])
{
    for (int i=0; i<13; i++)
        cout << "S: " << spade[i];
}

// To call it.
displayCards(spade);

---

Quote:

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Originally Posted by MacGyver

You're making up syntax here.

What is this?

Code:

---

displayCards(spade[0,13]);

---

Should be this:

Code:

---

displayCards(spade);

---

---

hahahaha yeah, i wasn't pt sure about that, but it compiled fine, and no one picked up on it so i thought i must of been right... but even after i fixed that up it still doesn't want to work for me! :( now i get

Quote:

---

19 expected `,' or `...' before "spade"
In function `void displayCards(std::string*)':
22 `spade' undeclared (first use this function)
[Build Error] [main.o] Error 1

---

Be careful of your case. In your early examples, you wrote it as Spade. Later, you wrote it as spade. You need to be consistent because C++ has case sensitive identifiers.

Quote:

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Originally Posted by laserlight

You are supposed to pass the variable spade, not spade[0,13] (is that even valid syntax?).

I am getting a little confused by Java at the moment, but in C++ I would write it as:

Code:

---

void displayCards(string spade[])
{
    for (int i=0; i<13; i++)
        cout << "S: " << spade[i];
}

// To call it.
displayCards(spade);

---

---

F@$k ME! after all that i just had to move the "[]" over, hahaha thanks for the help every one! :)

the joys of learning, really dose your head in at times

I was just curious, you can pass an array to an function, but can a function return an array?

Short answer is yes, but there's a few things to consider. When you pass an array to a function, you're really passing a pointer to the first element under the hood. You don't really see this, but it's vitality important to understanding how this works.

The pointer/array relationship becomes a little more apparent when trying to return an array. You end up having to return a pointer to the first element of the array. All good, right?

Well, here's another issue: You can't return local arrays. Local variables are destroyed some time around the end of the function because they are allocated on the stack. If you return a block of memory from a function, as a general rule you need to dynamically allocate it with new (or malloc() for C programs).