Using foreach with two types of conditions in c#

Question

I used dropdown for search. The text value should different from the value. So, I created 2 types of methods:

    List<string> lstRoles = new List<string>();
    lstRoles = _repository.GetRolesForFindJobseekers();
    List<string> lstFunctions = new List<string>();
    lstFunctions = _repository.GetFunctionsForRolesFindJobSeekers();


    List<SelectListItem> selectListRoles = new List<SelectListItem>();

    int i = 1;
    foreach (string role in lstRoles)
    {

            selectListRoles.Add(new SelectListItem
            {
                Text = role,
                Value = role,
                Selected = (i == 0)
            });

            i++;

    }
    ViewData["RolesForJobSeekers"] = selectListRoles;

lstFunctions should come in the value field. How will I add this?

maybe you can use a list of KeyValuePair where key is role and value is function? — mcy, Mar 10 '14 at 09:27
that depends on how you use your RolesForJobSeekers view data, if it is required by some framework you are using, name it so others can help, or consult it documentation. This is more than how to use that framework, than a c# foreach — Russell Yan, Mar 10 '14 at 09:32
if you're asking how to iterate two lists in parallel, see [this answer](http://stackoverflow.com/a/18396163/201088). — Eren Ersönmez, Mar 10 '14 at 09:38

score 4 · Answer 1 · answered Mar 10 '14 at 09:35

4

You could use linq and get it done in one query:

var selectListRoles =
    lstRoles
        .Zip(lstFunctions, (role, function) => new { role, function })
        .Select((rf, i) => new SelectListItem()
        {
            Text = rf.role,
            Value = rf.function,
            Selected = (i + 1 == 0),
        })
        .ToList();

ViewData["RolesForJobSeekers"] = selectListRoles;

answered Mar 10 '14 at 09:35

Enigmativity

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+1 my idea but sooner. The source enumerables don't need to be lists at all. – Jodrell Mar 10 '14 at 09:38
Ta. It's better if they are a list or an array. That ensures that the enumerable is executed once so that you don't get side effects. – Enigmativity Mar 10 '14 at 09:45
depends on the rest of the code, avoid multiple enumerations. – Jodrell Mar 10 '14 at 09:50

score 3 · Answer 2 · answered Mar 10 '14 at 09:30

3

Instead of foreach you can use enumerators to iterate over the two list in the same time

IEnumerator enum1 = lstRoles.GetEnumerator();
IEnumerator enum2 = lstFunctions.GetEnumerator();

int i = 1;
while ((enum1.MoveNext()) && (enum2.MoveNext()))
{
        selectListRoles.Add(new SelectListItem
        {
            Text = enum1.Current,
            Value = enum2.Current,
            Selected = (i == 0)
        });

        i++;
}

answered Mar 10 '14 at 09:30

Jaffa

12,442
4
49
101

3

you should use `using` for the enumerators. – Eren Ersönmez Mar 10 '14 at 09:34

Jodrell · Answer 3 · 2014-03-10T10:30:17.183

2

how about

var selectListRoles = _repository.GetRolesForFindJobseekers().Zip(
    _repository.GetFunctionsForRolesFindJobSeekers(),
    (role, function) => new SelectListItem
        {
            Text = role,
            Value = function,
            Selected = false
        }).ToList();
selectListRoles[0].Selected = true;
ViewData["RolesForJobSeekers"] = selectListRoles;

If you didn't want to instantiate selectListRoles

// If you know selectListRoles starts empty, use 0 instead of baseIndex.
var baseIndex = selectListRoles.Count;
selectListRoles.AddRange(_repository.GetRolesForFindJobseekers().Zip(
    _repository.GetFunctionsForRolesFindJobSeekers(),
    (role, function) => new SelectListItem
        {
            Text = role,
            Value = function,
            Selected = false
        }));
selectListRoles[baseIndex].Selected = true;

edited Mar 10 '14 at 10:30

answered Mar 10 '14 at 09:37

Jodrell

34,946
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2

It's a bad idea closing over an external variable in a query. You get the wrong results if the query is executed multiple times. – Enigmativity Mar 10 '14 at 09:44
@Enigmativity, I agree, its a dirty, and wasteful hack. – Jodrell Mar 10 '14 at 09:48
Now that's a better solution for this situation. I like it. – Enigmativity Mar 10 '14 at 09:48

score 2 · Accepted Answer · answered Mar 10 '14 at 09:44

You can first combine these 2 lists into one and then loop over that list.

var lstCombined =
    lstRoles
     .Zip(lstFunctions, (role, function) => new {Role = role, Function = function}).ToList();

int i = 1;

foreach (var item in lstCombined)
{
    selectListRoles.Add(new SelectListItem
                            {
                                Text = item.Role,
                                Value = item.Function,
                                Selected = (i == 0)
                            });

    i++;
}

Using foreach with two types of conditions in c#

4 Answers4