foreach, in (C# Reference)

The foreach statement repeats a group of embedded statements for each element in an array or an object collection that implements the System.Collections.IEnumerable or System.Collections.Generic.IEnumerable<T> interface. The foreach statement is used to iterate through the collection to get the information that you want, but can not be used to add or remove items from the source collection to avoid unpredictable side effects. If you need to add or remove items from the source collection, use a for loop.

The embedded statements continue to execute for each element in the array or collection. After the iteration has been completed for all the elements in the collection, control is transferred to the next statement following the foreach block.

At any point within the foreach block, you can break out of the loop by using the break keyword, or step to the next iteration in the loop by using the continue keyword.

A foreach loop can also be exited by the goto, return, or throw statements.

For more information about the foreach keyword and code samples, see the following topics:

Using foreach with Arrays

How to: Access a Collection Class with foreach

Example

The following code shows three examples.

Tip

You can modify the examples to experiment with the syntax and try different usages that are more similar to your use case. Press "Run" to run the code, then edit and press "Run" again.

  • a typical foreach loop that displays the contents of an array of integers
int[] fibarray = new int[] { 0, 1, 1, 2, 3, 5, 8, 13 };
foreach (int element in fibarray)
{
    System.Console.WriteLine(element);
}
System.Console.WriteLine();
// Output:
// 0
// 1
// 1
// 2
// 3
// 5
// 8
// 13
  • a for loop that does the same thing
int[] fibarray = new int[] { 0, 1, 1, 2, 3, 5, 8, 13 };
// Compare the previous loop to a similar for loop.
for (int i = 0; i < fibarray.Length; i++)
{
    System.Console.WriteLine(fibarray[i]);
}
System.Console.WriteLine();
// Output:
// 0
// 1
// 1
// 2
// 3
// 5
// 8
// 13
  • a foreach loop that maintains a count of the number of elements in the array
int[] fibarray = new int[] { 0, 1, 1, 2, 3, 5, 8, 13 };
// You can maintain a count of the elements in the collection.
int count = 0;
foreach (int element in fibarray)
{
    count += 1;
    System.Console.WriteLine("Element #{0}: {1}", count, element);
}
System.Console.WriteLine("Number of elements in the array: {0}", count);
// Output:
// Element #1: 0
// Element #2: 1
// Element #3: 1
// Element #4: 2
// Element #5: 3
// Element #6: 5
// Element #7: 8
// Element #8: 13
// Number of elements in the array: 8

C# Language Specification

For more information, see the C# Language Specification. The language specification is the definitive source for C# syntax and usage.

See Also

C# Reference

C# Programming Guide

C# Keywords

Iteration Statements

for