Possible to assign the Length of an array through a function with parameters?

Question

I'm having about 4 int arrays that need their length calculated, assigned to them and then populated. I was trying to thin out the code by using a function with parameters, instead of repeating long calculations 4 times, but I can't seem to set the length by designating the array as a parameter. I tried something like the code below:

for(int i=0; i<4; i++)
if(i==0) SetLength(array1);
else if(i==1) SetLength(array2);
else if(i==2) SetLength(array3);                   
else if(i==3) SetLength(array4);      

SetLength(int[] array)
{
    //calculations for length here
    //int result=...;

    array = new int[result];

    //getting info for populating the array
    for(int i=0; i<result; i++)
    array[i]=some_value[i];
}

Most of the code seems to work, except for the length assigning part. Any ideas?

array = new int[result]; Why you initializing array again in method? — Rohit Vats
– Rohit Vats, Commented Feb 1, 2014 at 18:48
That is the only way I know to assign a length, with "new int[nr]". Is there an other way? — Vantalk
– Vantalk, Commented Feb 1, 2014 at 18:51
Why not use a collection class List<T> or ArrayList which has .Add methods — Chris Hammond
– Chris Hammond, Commented Feb 1, 2014 at 18:52
The loop with the conditions is nonsense. You already write out the full code for all four iterations. Just write SetLength(array1); SetLength(array2); ... (with the fixes suggested by the answers). — user395760
– user395760, Commented Feb 1, 2014 at 18:54
@delnan Srry, you are right. I cut out a part of the code since it wasn't relevant in the example but I shouldn't of typed the conditions either. — Vantalk
– Vantalk, Commented Feb 1, 2014 at 19:03

MarcinJuraszek · Accepted Answer · 2014-02-01 18:50:21Z

5

If you need to reallocate the array within method and want it to update the variable you've passed as method parameter you have to make the parameter ref or out:

SetLength(ref int[] array)

for(int i=0; i<4; i++)
if(i==0) SetLength(ref array1);
else if(i==1) SetLength(ref array2);
else if(i==2) SetLength(ref array3);                   
else if(i==3) SetLength(ref array4);

answered Feb 1, 2014 at 18:50

MarcinJuraszek

126k15 gold badges200 silver badges267 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Chris Hammond · Accepted Answer · 2014-02-01 18:55:15Z

2

Why not use a collection class List or ArrayList which has .Add methods

answered Feb 1, 2014 at 18:55

Chris Hammond

2,2086 gold badges31 silver badges57 bronze badges

Comments

Ondrej Janacek · Accepted Answer · 2014-02-01 18:54:25Z

1

You can do it without ref modifier as MarcinJuraszek suggests like this

for(int i=0; i<4; i++)
if(i==0) array1 = SetLength();
else if(i==1) array2 = SetLength();
else if(i==2) array3 = SetLength();                   
else if(i==3) array4 = SetLength();      

int[] SetLength()
{
    //calculations for length here
    //int result=...;

    var array = new int[result];

    //getting info for populating the array
    for(int i=0; i < result; i++)
       array[i] = some_value[i];

    return array;
}

And by the way, you don't really need a cycle here. For your original code

SetLength(array1);
SetLength(array2);
SetLength(array3);                   
SetLength(array4);

would suffice.

answered Feb 1, 2014 at 18:54

Ondrej Janacek

12.6k14 gold badges62 silver badges96 bronze badges

Collectives™ on Stack Overflow

Possible to assign the Length of an array through a function with parameters?

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related