How to return an int array in C#

Question

I'm learning C# and I have a problem with a function.

It should multiply elements of the int array "tab" by the int value of "mnoznik" and return new int array "wyj".

I tried many things but I still have no idea on how to solve it.

static int mnozenie(int[] tab, int mnoznik)
{
    int[] wyj;
    wyj = new int[tab.Length];
    if (mnoznik != 0)
    {
        for (int i = 0; i < tab.Length; i++)
            wyj[i] = tab[i] * mnoznik;
        return wyj[];
    } else
        return 0;

Have your return type as int[][] and return null in else part. — Habib
– Habib, Commented Mar 30, 2015 at 18:00

puko · Accepted Answer · 2015-03-30 18:07:13Z

7

try

static int[] mnozenie(int[] tab, int mnoznik)
{
    int[] wyj = new int[tab.Length];
    if (mnoznik != 0)
    {
        for (int i = 0; i < tab.Length; i++)
            wyj[i] = tab[i] * mnoznik;
    }
    return wyj;

}

edited Mar 30, 2015 at 18:07

answered Mar 30, 2015 at 18:02

puko

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2 Comments

Peter Duniho Over a year ago

The OP wants the value 0 if the input mnoznik is 0. IMHO, that means it would make more sense to always return wyj; and just skip the multiplication loop if mnoznik is 0.

Ola Ström Over a year ago

This worked perfectly (to create and return an int array)...

Ola Ström · Accepted Answer · 2023-02-12 17:20:44Z

1

static int[] mnozenie(int[] tab, int mnoznik)
{
    if (tab.Length > 0)
    {
        for (int i = 0; i < tab.Length; i++)
        {
            tab[i] *= mnoznik;
        }
        return tab;
    }
    return null;
}

Or alternatively instead of return null just return tab back.

The if block just protects from trying to access a null collection, or you could just handle the exception in whatever way you choose.

edited Feb 12, 2023 at 17:20

Ola Ström

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answered Mar 30, 2015 at 18:38

unoriginal

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7 Comments

unoriginal Over a year ago

or alternatively instead of return null just return tab back, the if block just protects from trying to access a null collection, or just handle the exception in whatever way you choose.

puko Over a year ago

where u store result of multiplication ?

puko Over a year ago

yes u assign result to local field item which is never declared ... in the original method is result of multiplication stored in array

unoriginal Over a year ago

I'm sorry, but thats just not accurate. If the original int[] tab is never declared then that is handled with the if block, if it is declared then I store the result of the multiplication for each element in the element and pass the new int[] tab back. In fact declaring another int[] or any more variables would be a complete waste of resources as they are unneeded.

unoriginal Over a year ago

furthermore, you are welcome and even encouraged to test the above code to see if it works.

|

f00f · Accepted Answer · 2015-03-30 18:09:11Z

0

You're trying to return both an array and an integer, which you can't do. You can wrap it all in a Tuple<,> and return both, or you can return null in the case mnoznik is 0.

Something like:

static Tuple<bool,int[]> mnozenie(int[] tab, int mnoznik)
{
    return (mnoznik == 0)
           ? new Tuple<bool,int[]>(false, new [] { 0 })
           : new Tuple<bool,int[]>(true, tab.Select(i => i*mnoznik).ToArray());
}

or

static int mnozenie(int[] tab, int mnoznik)
{
    return (mnoznik == 0)
           ? null
           : tab.Select(i => i*mnoznik).ToArray();
}

answered Mar 30, 2015 at 18:09

f00f

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2 Comments

puko Over a year ago

in your second example has method int return type and u returned int array

f00f Over a year ago

That was a typo. I should've written int[]. Another thing is that instead of null, you might return a well-defined array, like I did in the first example: new [] { 0 };

nightooi · Accepted Answer · 2021-04-24 10:46:01Z

0

correct me if I'm wrong but I'm something like 90% sure that in case of returning arrays or any kind of element in c#/c++. The compiler actually doesn't actually move the value itself, in the stack from one memory location to another, it just pushes the pointer/handle to that specific memory, where the information is stored up the stack.

by specifying

return wyj[];

you're actually trying to return the array itself, and not the pointer. Which would be illegal, but my simply removing the the square brackies, you're moving the pointer and complier is happycamper. [EDIT: missed words]

answered Apr 24, 2021 at 10:46

nightooi

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Comments

Ola Ström · Accepted Answer · 2023-02-12 17:17:51Z

0

Try to see if this code might be able to help you!

static int[] m(int[] a , int low , int big) 
{
    int[] re = new int[2];
    int min, max, mid ;
    if (low == big)
    {
        min = max = a[low];
        re[0] = min;
        re[1] = max;
        return (re);
    }
}

edited Feb 12, 2023 at 17:17

Ola Ström

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answered Mar 8, 2018 at 10:20

mahdibahramih

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