Adding an int to an existing array of its

Question

Here is my code I have tried

int[] WeeklyTotal = new int[53];
for (int w = 1; w <= 53; w++)
{
    WeeklyTotal[w] = WeeklyTotal[w] + data.Rows[i]["week" + w];  // Error is here
}

But I'm getting a compile error:

Can not apply opperator + to opperands of type int and object

What is the correct syntax here?

Thanks!

Also C# arrays are zero indexed, you need change for (int w = 1; w <= 53; w++) to for (int w = 0; w < 53; w++) — Valentin
– Valentin, Commented Aug 4, 2016 at 15:23
Instead of casting you could also use DataRowExtension.Field: int weekValue = data.Rows[i].Field<int>("week" + w) — Tim Schmelter
– Tim Schmelter, Commented Aug 4, 2016 at 15:26

MMK · Accepted Answer · 2016-08-04 15:56:37Z

5

You need to cast object type to integer type

WeeklyTotal[w] = WeeklyTotal[w] + (int)data.Rows[i]["week" + w];

also your array iteration for loop logic needs to be updated otherwise index will be outside the range and it will throw IndexOutOfRangeException

for (int w = 0; w < WeeklyTotal.Length; w++)
{
    WeeklyTotal[w] = WeeklyTotal[w] + (int)data.Rows[i]["week" + w];
}

edited Aug 4, 2016 at 15:56

MMK

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answered Aug 4, 2016 at 15:21

Mostafiz

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Comments

Dmitrii Bychenko · Accepted Answer · 2016-08-04 15:47:31Z

2

if the object really is a boxed integer use (int) Cast operator else use Convert.ToInt32()

edited Aug 4, 2016 at 15:47

Dmitrii Bychenko

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answered Aug 4, 2016 at 15:26

MMK

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1 Comment

Dmitrii Bychenko Over a year ago

Yes, Convert is a better alternative to cast in the context: data.Rows[i] can well return boxed short or, say, String (e.g. "123 ") if database field is of wrong type etc.

Matt · Accepted Answer · 2016-08-04 15:22:16Z

1

Need to cast object type as an integer:

WeeklyTotal[w] = WeeklyTotal[w] + (int)data.Rows[i]["week" + w];

answered Aug 4, 2016 at 15:22

Matt

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Comments

René Vogt · Accepted Answer · 2016-08-04 15:24:47Z

As others already pointed out, you have to cast the object returned by data.Rows[i]["week" + w] to int.

But more important your for loop is buggy and will cause an IndexOutOfRangeException.

Arrays are zero-indexed in c#, so your loop should run from 0 to 52 or you have to decrease w by one when accessing the array:

int[] WeeklyTotal = new int[53];
for (int w = 1; w <= 53; w++)
{
    WeeklyTotal[w-1] = WeeklyTotal[w-1] + (int)data.Rows[i]["week" + w];
}

or

int[] WeeklyTotal = new int[53];
for (int w = 0; w < 53; w++)
{
    WeeklyTotal[w] = WeeklyTotal[w] + (int)data.Rows[i]["week" + (w+1)];
}

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