Funcions-can they return more than 1 value?

Hi,

Just practising making my own header files and functions.I have created a function that generates 4 different varibles.I have set the function to return all 4.It compiles fine but when i call the function in main and then try and cout the 4 values the programme just closes without any out put.

Have tried to include the 'couting'(if you get my meaning:)) of the value's within the function,but the compiler starts showing an error(cout-undeclared identifier).
Any ideas?

Pass pointers (or better, references) to where you want the additional answers stored.

Or create a struct containing all 4 values, then return that struct by value (not so good if the contained data is on the large side).

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but the compiler starts showing an error(cout-undeclared identifier)

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did you include iostream?
did you tell the compiler it's part of the std namespace?

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can they return more than 1 value?

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they can be returned in the form of an array, struct or class

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the programme just closes without any out put

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did you tell it to wait after it couts the 4 variables?

it'd be easier for us if you showed us some code

only started C++ recently and am only reading up on pointers at the moment so that's beyond me at the oment but thanks anyway

Labmouse

Didnt include <iostream> in the header file but have in main().And also used cin.get() after the 4 couts in main.And also using namespace std in main.

heres my header file

Code:

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#ifndef myfunctions_h
#define myfunctions_h



int randomNumbers()
{
       
                        int a=(rand()%24)+1;
                        int b=(rand()%24)+1;
                        int c=(rand()%24)+1;
                        int d=(rand()%24)+1;
           

                        return a,b,c,d;
}



#endif

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Originally Posted by Labmouse

heres my header file

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Bad practice to place function definitions inside header files. You at the very least need to use the "inline" keyword.

Also, "return a,b,c,d;" just returns the value in d, not all four values. Like other people said you need to return an array or object, or pass the a,b,c,d as reference parameters.

Ah ok so just function prototypes in the header file.So it will only return one varible.Haved learnt the use of pointers or structures yet so that path is a no go at the moment

Thanks all

You could just make the function return one random number and then call it 4 times.

References are horrifically easy:

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void my_func(int& param1, int& param2, int& param3, int& param4)
{
        param1 = 1;
        param2 = 2;
        param3 = 3;
        param4 = 4;
}

int main()
{
        int a,b,c,d;
        my_func(a, b, c, d);
        // a = 1, b = 2, c = 3, d = 4
}

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All you need to do is put a & at the arguments and the function can modify these arguments when you pass variables to it.

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Originally Posted by Labmouse

Code:

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                        int a=(rand()%24)+1;
                        int b=(rand()%24)+1;
                        int c=(rand()%24)+1;
                        int d=(rand()%24)+1;

---

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More than two lines the same = use an array instead.

Personally if I wanted to generate four random numbers I would make a function that generates and returns a number then call it four times instead.

Alternatively you could make it a bit more flexible by passing an array to the function, then get its size and generate a random number for each element in the array. That way the function would deal with whatever amount of numbers you wanted to generate for it and you wouldn't need a load of parameters. Just an idea.

As for cout being an undeclared identifier: Are you using standard namespace? I got the same error message everytime I forgot about it.

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Originally Posted by h_howee

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can [functions] return more than 1 value?

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they can be returned in the form of an array, struct or class

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Structs or classes, yes. Arrays are tricky to return from functions, though. The simplest way to do it is to make the array static and return a pointer. Or allocate some memory for the array and return that. Or just pass the array into the function as a parameter in the first place . . .

Any way you look at it, you end up using pointers instead of arrays.

encapsulate them (i.e put them in a struct, array or class) then return them. best and simplest way to do this (although is doesn't seem that easy but it is) is to encapsulate them in a class then define your own cout output operator for that class. Sounds hard but it's really easy (imo anyways)

Thanks...in hindsight making a function that returns 1 random number and then calling it 4 times is fairly goddamm obvious!!