CODEWITHSUNDEEP
c#foreachkeywordwhile-loopcontinue
Amr
Amr

Reputation: 1995

Continue in while inside foreach

In the following C# code snippet
I have a 'while' loop inside a 'foreach' loop and I wish to jump to the next item in 'foreach' when a certain condition occurs.

foreach (string objectName in this.ObjectNames)
{
    // Line to jump to when this.MoveToNextObject is true.
    this.ExecuteSomeCode();
    while (this.boolValue)
    {
        // 'continue' would jump to here.
        this.ExecuteSomeMoreCode();
        if (this.MoveToNextObject())
        {
            // What should go here to jump to next object.
        }
        this.ExecuteEvenMoreCode();
        this.boolValue = this.ResumeWhileLoop();
    }
    this.ExecuteSomeOtherCode();
}

'continue' would jump to the beginning of the 'while' loop not the 'foreach' loop. Is there's a keyword to use here, or should I just use goto which I don't really like.

Upvotes: 3

Views: 24075

Answers (5)

erikkallen
erikkallen

Reputation: 34421

Use goto.

(I guess people will be mad with this response, but I definitely think it's more readable than all other options.)

Upvotes: 1

Henk Holterman
Henk Holterman

Reputation: 273804

The following should do the trick

foreach (string objectName in this.ObjectNames)
{
    // Line to jump to when this.MoveToNextObject is true.
    this.ExecuteSomeCode();
    while (this.boolValue)
    {
        if (this.MoveToNextObject())
        {
            // What should go here to jump to next object.
            break;
        }
    }
    if (! this.boolValue) continue; // continue foreach

    this.ExecuteSomeOtherCode();
}

Upvotes: 4

Chris Hynes
Chris Hynes

Reputation: 10239

Use the break keyword. That will exit the while loop and continue execution outside it. Since you don't have anything after the while, it would loop around to the next item in the foreach loop.

Actually, looking at your example more closely, you actually want to be able to advance the for loop without exiting the while. You can't do this with a foreach loop, but you can break down a foreach loop to what it actually automates. In .NET, a foreach loop is actually rendered as a .GetEnumerator() call on the IEnumerable object (which your this.ObjectNames object is).

The foreach loop is basically this:

IEnumerator enumerator = this.ObjectNames.GetEnumerator();

while (enumerator.MoveNext())
{
    string objectName = (string)enumerator.Value;

    // your code inside the foreach loop would be here
}

Once you have this structure, you can call enumerator.MoveNext() within your while loop to advance to the next element. So your code would become:

IEnumerator enumerator = this.ObjectNames.GetEnumerator();

while (enumerator.MoveNext())
{
    while (this.ResumeWhileLoop())
    {
        if (this.MoveToNextObject())
        {
            // advance the loop
            if (!enumerator.MoveNext())
                // if false, there are no more items, so exit
                return;
        }

        // do your stuff
    }
}

Upvotes: 9

andleer
andleer

Reputation: 22578

You can use "break;" to exit the innermost while or foreach.

Upvotes: 0

Mitch Wheat
Mitch Wheat

Reputation: 300789

The break; keyword will exit a loop:

foreach (string objectName in this.ObjectNames)
{
    // Line to jump to when this.MoveToNextObject is true.
    while (this.boolValue)
    {
        // 'continue' would jump to here.
        if (this.MoveToNextObject())
        {
            break;
        }
        this.boolValue = this.ResumeWhileLoop();
    }
}

Upvotes: 2

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