Information Technology Reference
In-Depth Information
The foreach Statement
The
foreach
statement allows you to sequentially access each element in an array. It is actually
a more general construct in that it also works with other collection types—but this section will
only discuss its use with arrays. Chapter 20 will cover its use with other collection types.
The important points of the
foreach
statement are the following:
The
iteration variable
is a temporary, read-only variable of the same type as the ele-
ments of the array. The
foreach
statement uses the iteration variable to sequentially
represent each element in the array.
The syntax of the
foreach
statement is where
-
Type
is the type of the elements of the array.
-
Identifier
is the name of the
iteration variable
.
-
ArrayName
is the name of the array to be processed.
-
Statement
is a simple statement or a block that is executed once for each element in
the array.
Iteration variable declaration
↓
foreach(
Type Identifier
in
ArrayName
)
Statement
The way the
foreach
statement works is the following:
It starts with the first element of the array and assigns that value to the
iteration variable
.
It then executes the body of the statement. Inside the body, you can use the iteration
variable as a read-only alias for the array element.
After the body is executed, the
foreach
statement selects the next element in the array
and repeats the process.
In this way, it cycles through the array, allowing you to access each element one by one.
For example, the following code shows the use of a
foreach
statement with a one-dimensional
array of four integers:
The
WriteLine
statement, which is the body of the
foreach
statement, is executed once
for each of the elements of the array.
The first time through the loop, iteration variable
item
has the value of the first element
of the array. Each successive time, it will have the value of the next element in the array.
int[] arr1 = {10, 11, 12, 13};
Iteration variable declaration
↓
Iteration variable use
foreach( int item in arr1 )
↓
Console.WriteLine("Item Value: {0}", item);
