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c#.netloops
Brian
Brian

Reputation: 8377

How do I skip an iteration of a `foreach` loop?

In Perl I can skip a foreach (or any loop) iteration with a next; command.

Is there a way to skip over an iteration and jump to the next loop in C#?

 foreach (int number in numbers)
 {
     if (number < 0)
     {
         // What goes here to skip over the loop?
     }

     // otherwise process number
 }

Upvotes: 391

Views: 525091

Answers (8)

drewh
drewh

Reputation: 10167

Use the continue statement:

foreach(object number in mycollection) {
     if( number < 0 ) {
         continue;
     }
  }

Upvotes: 14

Kashif
Kashif

Reputation: 38

The easiest way to do that is like below:

//Skip First Iteration

foreach ( int number in numbers.Skip(1))

//Skip any other like 5th iteration

foreach ( int number in numbers.Skip(5))

Upvotes: -4

Edmund Covington
Edmund Covington

Reputation: 521

Another approach using linq is:

foreach ( int number in numbers.Skip(1))
{   
    // process number  
}

If you want to skip the first in a number of items.

Or use .SkipWhere if you want to specify a condition for skipping.

Upvotes: 16

John Feminella
John Feminella

Reputation: 311745

You want:

foreach (int number in numbers) //   <--- go back to here --------+
{                               //                                |
    if (number < 0)             //                                |
    {                           //                                |
        continue;   // Skip the remainder of this iteration. -----+
    }

    // do work
}

Here's more about the continue keyword.

Update: In response to Brian's follow-up question in the comments:

Could you further clarify what I would do if I had nested for loops, and wanted to skip the iteration of one of the extended ones?

for (int[] numbers in numberarrays) {
  for (int number in numbers) { // What to do if I want to
                                // jump the (numbers/numberarrays)?
  }
}

A continue always applies to the nearest enclosing scope, so you couldn't use it to break out of the outermost loop. If a condition like that arises, you'd need to do something more complicated depending on exactly what you want, like break from the inner loop, then continue on the outer loop. See here for the documentation on the break keyword. The break C# keyword is similar to the Perl last keyword.

Also, consider taking Dustin's suggestion to just filter out values you don't want to process beforehand:

foreach (var basket in baskets.Where(b => b.IsOpen())) {
  foreach (var fruit in basket.Where(f => f.IsTasty())) {
    cuteAnimal.Eat(fruit); // Om nom nom. You don't need to break/continue
                           // since all the fruits that reach this point are
                           // in available baskets and tasty.
  }
}

Upvotes: 810

Kev
Kev

Reputation: 119856

You can use the continue statement.

For example:

foreach(int number in numbers)
{
    if(number < 0)
    {
        continue;
    }
}

Upvotes: 18

Dustin Campbell
Dustin Campbell

Reputation: 9865

Another approach is to filter using LINQ before the loop executes:

foreach ( int number in numbers.Where(n => n >= 0) )
{
    // process number
}

Upvotes: 60

crashmstr
crashmstr

Reputation: 28583

You could also flip your if test:


foreach ( int number in numbers )
{
     if ( number >= 0 )
     {
        //process number
     }
 }

Upvotes: 28

Tamas Czinege
Tamas Czinege

Reputation: 121424

foreach ( int number in numbers )
{
    if ( number < 0 )
    {
        continue;
    }

    //otherwise process number
}

Upvotes: 26

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