How do I access each element in foreach?

Question

1.00/5 (1 vote)

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When we write a query using linq
Then we say
Foreach (var x in query)
{
}
Let's say query has object[0] and object[1] and each object has different field values

What I have tried:

Inside the for each i saw
X.elementAt(0). Fieldvalue but i don't want to specify 0 i want it take the current index of the for each... How can i
do this?  In order to get the correct result and not get the result of object 0 in each time

Posted 16-Apr-20 9:27am

Member 14800672

Updated 16-Apr-20 10:22am

v3

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Maciej Los 16-Apr-20 16:00pm

How does look like your query?

Member 14800672 16-Apr-20 23:56pm

Table has Id1,Id1,Num1,Num2 fields
var query = Table
.GroupBy(x => new { x.Id1, x.Id2 })
.Select(g => new
{
Id1 = g.Key.Id1,
Id2 = g.Key.Id2,
groupedBy = g

})
foreach (var group in query)
{
// number class takes two double values
Number number = new Number(group.num1, group.num2); // i can't get to num1 and num2
}

i tried this but still i have error
group.groupedBy.Select(x=> x.num1)
the error : can't convert from Ienumrable<double> to double

Member 14800672 17-Apr-20 0:10am

i think i need to do
Number number = new Number(group.groupedBy.First().num1,group.groupedBy.First().num2);

btw what is the benefit of .Select i made in the query? i still can access Id1 and Id2 without it.. in that case i will put group.First().num1 or any other field so when should i put .Select in query?

2 solutions

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OriginalGriff · Answer 1 · 2020-04-16T10:02:00

You can't access the "index" of a foreach, because it doesn't necessarily have one - A foreach operates on an iterator, and how that is implemented is down to the collection itself, not the IEnumerable interface that allows a collection to work with foreach

If you need an index, then use a for loop instead of foreach and provide the index yourself.

phil.o · Answer 2 · 2020-04-16T10:01:00

Solution 1

You do not have indices in a foreach loop, you can use the variable itself:

C#

foreach (var x in query)
{
   // the x variable is the current element
}

// is equivalent to

for (int i = 0; i < query.Count(); ++i)
{
   var x = query[i];
}

If you really need the current index, then you can create a variable and increment it in the loop:

C#

int index = -1;
foreach (var x in query)
{
   ++index;
   // ...
}

Posted 16-Apr-20 10:01am

phil.o

Comments

Member 14800672 16-Apr-20 16:33pm

As i said query has object[0] which has two fields Id=1,name =name1and it also has object[1] which has Id=2,name=name2
Now when i write
Foreach(var x in query)
{
// i want to store the names
// x. What?
String value += x.
}

phil.o 16-Apr-20 17:04pm

string currentName = x.name;

BillWoodruff 19-Apr-20 1:26am

+5