C# iterate through 2d array

Question

I the following array:

And I need to output the values as follows:

"API Docs Portal : op-api-docs"
"Big Ideas : op-bigideas"
"Education : op-education"
....

I've tried something but it doesn't works as expected...

        for (var x = 1; x <= reportValue.GetLength(0); x++)
        {
            for (var y = 1; y <= reportValue.GetLength(1); y++)
            {
                if (reportValue[x, y] != null)
                {
                    var id = reportValue[x, y];
                    var name = reportValue[x, y + 1];
                    var result = name + " : " + id;
                }
            }
        }

Note:
This is how I get the reportValue array (using C# Interop):

    var reportLast = ws.Range["A" + ws.Rows.Count].End(Excel.XlDirection.xlUp).Row;
    var rngReport = (Excel.Range)ws.Range[ws.Cells[2, 1], ws.Cells[reportLast, 2]];
    var reportValue = rngReport.Cells.Value;

Are you sure this is a 2d-array? Because usually indices start at 0... — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Mar 24, 2017 at 14:36
@WillemVanOnsem: Usually, yes - but they certainly don't have to. If you look at the debugger screenshot, this does indeed appear to be 1-based. — Jon Skeet
– Jon Skeet, Commented Mar 24, 2017 at 14:38
" it doesn't works as expected..." doesn't tell us either what you expected, or what happened. Please provide a minimal reproducible example. — Jon Skeet
– Jon Skeet, Commented Mar 24, 2017 at 14:39
Your use of reportValue[x, y + 1] looks pretty suspicious to me... — Jon Skeet
– Jon Skeet, Commented Mar 24, 2017 at 14:40
The 2nd loop is unnecessary, and in fact will read off the end of the array — Iain Brown
– Iain Brown, Commented Mar 24, 2017 at 14:40

Jon Skeet · Accepted Answer · 2017-03-24 14:40:57Z

5

It's not clear why you've got two loops here. You always want the same two elements for each row - index 1 and index 2. So you just need:

for (var x = 1; x <= reportValue.GetLength(0); x++)
{
    var id = reportValue[x, 1];
    var name = reportValue[x, 2];
    var result = name + " : " + id;
    // Use result
}

That will fetch [1, 1] : [1, 2], then [2, 1] : [2, 2], then [3, 1] : [3, 2] etc - which looks like it's exactly what you need.

answered Mar 24, 2017 at 14:40

Jon Skeet

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2 Comments

Valip Over a year ago

Yes, this is exactly what I need! It seems that the array is 1d...is this correct?

rtlayzell Over a year ago

There are 2 dimensions to the array, but the "2nd dimension" is merely a key-value pair, it has a fixed length of 2. So you only need to iterate over the the "1st dimension" which seems to be of variable length... Not sure that makes sense to anyone besides myself...

Community · Accepted Answer · 2020-06-20 09:12:55Z

0

Best way for transform 2D array to string in this format is:

var results = string.Join(Environment.NewLine, array.Select(x => string.Join(" : ", x)));

For this array as example:

var array = new string[][]
{
    new string[] { "Hello world", "Hello" },
    new string[] { "Stack", "Overflow" }
};

Output for 'results' is:

Hello world : Hello

Stack : Overflow

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Mar 24, 2017 at 14:46

Ivan Kishchenko

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Comments

Nathangrad · Accepted Answer · 2017-03-24 14:48:05Z

0

The title is somewhat misleading as it doesn't appear to be a standard 2D array.
Nevertheless:

StringBuilder builder = new StringBuilder();
for (int i = 1; i <= reportValue.GetLength(0); i++)
{
    string id = (string)reportValue[i, 1];
    string name = (string)reportValue[i, 2];
    builder.AppendLine(id + " : " + name);
}
// Process the result

This begins a for loop at 1 as the array appears to be 1-based as opposed to 0-based.
Assuming that there is only two values that you require, you can use [i, 1] and [i, 2] rather than looping through the length of the secondary part using GetLength(1).

answered Mar 24, 2017 at 14:48

Nathangrad

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