Foreach Question

Question

Greetings,

I am new to c# programming. Is it possible to include a conditional if else statement nested within a foreach iteration. I've been working on this the last couple of days to no avail. The if part of the statement works, but the else statement seems to get skipped. Just need some confirmation on the matter. Thanks in advance to all.

Rich

Vulpes · Answer

One possibility is that the foreach statement is not being entered at all when the username or password is invalid. I'd try inserting this line just before the foreach: MessageBox.Show(query.Count().ToString()); I always paste code from VS into notepad first and from there into the reply box. Otherwise, it tends to be all over the place as you say.

Vulpes · Answer

Pleased to hear you've figured it out now, Rich :) Yes, if the collection (i.e. 'query' in this case) is empty, the code in the foreach block never executes but no exception is thrown. When something in a foreach is not happening but should happen, then this is often the reason why.

Rich · Answer

Vulpes, That solved it! The foreach block never ran when the requested info was invalid as you stated. I moved the message box from within the else block to in between the linq query and foreach block. here is the fix: if (query.Count().ToString() == "0") { string message = "Wrong user name or password."; string caption = "Invalid User Name or Password."; MessageBoxButton Button = MessageBoxButton.OK; MessageBoxImage Icon = MessageBoxImage.Warning; MessageBox.Show(message, caption, Button, Icon); } I assume since the query returned 0, the foreach block did not have a reason to execute. Thanks for the help and insight from everyone. Rich

Suthish Nair · Answer

You must simply put a break point and apply Quick Watch and check the object value during run time..

Sam Hobbs · Answer

In C# and the languages (C, C++ and Java at least) with the same syntax the curly braces ("{}") are used to specify a block. A block can be used anywhere that a single statement can be used. So a foreach statement just executes a single statement but that statement can be a block containing many statements. For example the following is a modified version of a portion of Vulpes's code. This is syntactically correct and work as intended. Most programmers would not do this but regardlous of the style it is valid. foreach(char c in "abcdefgh") if (c == 'a' || c == 'e') Console.Write('z'); else Console.Write(c);

Rich · Answer

Great suggestions! I will try these out and get back to you guys with the results.

Prabhu Raja · Answer

Hi, You may first Check Username and Password Value after entering into foreach loop by, foreach (var userItem in query) { // Display message Box to Conform All Values in If Condition are Present. MessageBox.Show("UserName is "+ UserItem.User.ToString()+ " = " +userName.ToString() + " And Password is "+userItem.Password.ToString()+" = " +password.ToString()); if ((userItem.User.ToString() == userName) && (userItem.Password.ToString() == password)) { User SiteDirector = new User(); SiteDirector.DirectorUserName = userItem.User.ToString(); Users.NavDirector NavDirector = new Users.NavDirector(); NavDirector.Show(); } else { string message = "Wrong user name or password."; string caption = "Invalid User Name or Password."; MessageBoxButton Button = MessageBoxButton.OK; MessageBoxImage Icon = MessageBoxImage.Warning; MessageBox.Show(message, caption, Button, Icon); } }

Prabhu Raja · Answer

Recently i had posted a thread, related to your query. For example: int[] array = { 1, 2, 3, 4, 5, 6, 7, 8, 9 }; // Print. foreach (int value in array) { for (int i = 0; i this.TextBox1.Text += value.ToString(); this.TextBox1.Text += System.Environment.NewLine; } // Reverse. Array.Reverse(array); // Print. foreach (int value in array) { for (int i = 0; i { this.TextBox1.Text += value.ToString(); } if (value != 9 ) this.TextBox1.Text += System.Environment.NewLine; } The output will be: 1 22 333 4444 55555 666666 7777777 88888888 999999999 88888888 7777777 666666 55555 4444 333 22 1 The If and for loop works perfectly for me.

Rich · Answer

Well, right now the query is pulling the data from an entity class which currently only holds one user name and password. This foreach block is part of a button click method in a wpf. When i enter the correct information the program proceeds as expected. When I then enter incorrect information I get no response from the program; I click the button and nothing happens. On a side note. Is there a certain way to paste the code into this post, or is just manually typing it the best way, as my code is all over the place in the previous post, lol.

Vulpes · Answer

Your code looks OK to me. How many userItems could be in 'query' and are you sure that at least one of them has an invalid user name or password?

Rich · Answer

Ok, here's the code. Sorry for leaving it out of the initial post. foreach ( var userItem in query) { if ((userItem.User.ToString() == userName) && (userItem.Password.ToString() == password)) { User SiteDirector = new User (); SiteDirector.DirectorUserName = userItem.User.ToString(); Users. NavDirector NavDirector = new Users. NavDirector (); NavDirector.Show(); } else { string message = "Wrong user name or password." ; string caption = "Invalid User Name or Password." ; MessageBoxButton Button = MessageBoxButton .OK; MessageBoxImage Icon = MessageBoxImage .Warning; MessageBox .Show(message, caption, Button, Icon); } } I am simply trying to get message box to show when either the password or username is incorrect. I have confirmed that the first part works, as it executes correctly when the appropriate username and password is supplied, but the else statement doesn't seem to be recognized. The program builds with out errors, so I am a bit clueless here.

Vulpes · Answer

I thought it might help if I wrote a simple example of using an if/else statement within a foreach block: using System; class Test { static void Main() { foreach(char c in "abcdefgh") { if (c == 'a' || c == 'e') { Console.Write('z'); } else { Console.Write(c); } } Console.WriteLine(); Console.ReadKey(); } } The output should be : zbcdzfgh

Rakesh Jha · Answer

Yes, you can. you can also use switch statement but i suppose you should include your code, so that we can easily identify error.

Vulpes · Answer

Yes, you can include an if/else statement (or, for that matter, any other type of statement) in a foreach block. If you can post your code, then we can take a look at it.