For each

Typically the performance of a foreach loop shouldn't be extraordinarily slower than that of a for-loop (it will be slower but not significantly). With that said, you can use a forloop to handle this same logic as seen below :

for(int i = 0; i < rowsthree.Count(); i++)
{
      //Rather than referencing by "row" as you did previously, you will use rowsthree[i]
      var row = rowsthree[i];
}

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ssvikramuk

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229 Points

662 Posts

Re: For each

May 08, 2013 01:56 PM|ssvikramuk|LINK

Rion, As per your above code I have modified a little bit, but it throws an error,

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0841: Cannot use local variable 'rowsthree' before it is declared

Source Error:

Line 12: 
Line 13:                     for(int i = 0; i < rows.Count(); i++){
Line 14: var row = rowsthree[i];

 var db = Database.Open("sls");
    var rows = db.Query(@"SELECT postingID, title, shortdescription, SUBSTRING(description, 1, 100) as description FROM Posting " +
                "LEFT OUTER JOIN Categories ON Posting.category = Categories.categoryID " +
                "WHERE Categories.categoryID = 1 ORDER BY Posting.postingID DESC");
 
 
                    var data = "";
 
                    data+="<div id='resultone' class='col span_1_of_4' style='padding: 0.1px; '>";
 
                    for(int i = 0; i < rows.Count(); i++){
                    var row = rowsthree[i];
                     data +=
                            "<div style='padding:4%; box-shadow: 3px 1px 3px #b6b6b6; -webkit-box-shadow: 3px 0px 5px -2px #888; margin-bottom:14px;' class='section group siteimage'>"+
            "<div><h2><p style='white-space: normal;'><a data-ajax='false' style='color:#5a5a5a;' href=PostingDetails.cshtml/" +row.postingID + ">"+ row.title + "</a></p></h2>"+
               "<a data-ajax='false' style='color:#5a5a5a;' href=PostingDetails.cshtml/" +row.postingID + ">"+
                                String.Format("<p><img class='large-photo' alt='' src='{0}' /></p>",Href("~/Thumbnail", row.postingID, new { size="medium" })) +
                                "</a>"+

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Rion William...

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Re: For each

May 08, 2013 02:31 PM|Rion Williams|LINK

I had assumed that rowsthree was the name of your "rows" collection.

Based on the code that you provided you would want to just use "rows" instead :

for(int i = 0; i < rows.Count(); i++){
      //Refer to your row here
      var row = rows[i];
}

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ssvikramuk

Member

229 Points

662 Posts

Re: For each

May 08, 2013 02:33 PM|ssvikramuk|LINK

Thanks Rion. Am getting the below error now

Compiler Error Message: CS0021: Cannot apply indexing with [] to an expression of type 'System.Collections.Generic.IEnumerable<dynamic>'

Source Error:

Line 15:                     for(int i = 0; i < rows.Count(); i++){
Line 16:                       //Refer to your row here
Line 17: var row = rows[i]; Line 18:

Reply

oned_gk

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Re: For each

May 08, 2013 09:22 PM|oned_gk|LINK

if you want data manipulation, i think in rowdatabound event will better performance instead looping all rows.

Programming to simplify, don't look for difficult way
Suwandi - Non Graduate Programmer

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akhleshchauh...

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Re: For each

May 09, 2013 01:04 AM|akhleshchauhan|LINK

if you are using > 3.5 fraimework then use

Parallel.ForEach

http://codingcramp.blogspot.in/2011/02/c-parallelforeach-simple-example.html

Thank You,
Akhlesh Chauhan

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Rion William...

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Re: For each

May 09, 2013 08:00 AM|Rion Williams|LINK

I'm not sure why you would be continually encountering performance issues based on the type of loop that you are using. The performance of foreach and a for loop should be relatively close, which leads me to believe that the issue could actually be related to your database query that may be slowing things down.

Are you recieving any intellisense when you are using the following code :

for(int i = 0; i < rows.Count(); i++){
      //Check the following for intellisense
      var row = rows[i];
}

As the Database.Query() method that you are using returns an IEnumerable<Object> so you should be able to access the values accordingly. You may want to try not using var and instead using an object instead to see if that makes any difference and you should be able to refer to your explicit columns as well :

for(int i = 0; i < rows.Count(); i++){
      //Example of using an object
      object row = rows[i];

      //Example of explicitly trying to access a row property
      var property = rows[i]["Your Column Name"];
}

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