C# Foreach: what it is, How it works, Syntax and Example Code

In modern programming, loops play a fundamental role in optimizing and simplifying the coding process. Loops are conditional iterative instructions that execute a block of statements until the test condition stays true. They carry out a repeated sequence without the need to write codes repeatedly. The most common examples of loops in programming include the while loop and the for a loop.

Introduction to foreach in C#

The foreach loop in C# iterates items in a collection, like an array or a list. It proves useful for traversing through each element in the collection and displaying them. The foreach loop is an easier and more readable alternative to for loop.

How Does It Work?

The foreach loop in C# uses the ‘in’ keyword to iterate over the iterable item.

The in keyword selects an item from the collection for the iteration and stores it in a variable called the loop variable, and the value of the loop variable changes in every iteration. For example, the first iteration process will have the first item of the collection stored; the second iteration will have the second item of the collection stored, and so on.

The number of iterations of the C# foreach loop equals the total items in the collection. Here’s a flowchart showing the working of the C# foreach loop.

C_Sharp_foreach_1.

A few key points to note:

All the statements of the foreach loop must be enclosed within curly braces { }.
The Foreach loop uses the loop variable instead of the indexed element to perform the iteration.
The C# foreach loop only requires the declaration of a variable with the same data type as the base type of the collection or array instead of a loop counter variable.

The Syntax of C# foreach

Here is the syntax of C# foreach loop.

foreach (datatype variable name in iterable-item)

{

// body of the loop

}

Sample Code to Understand the Working of C# foreach

Here’s a basic program to understand the working of the foreach loop. In this program, we’ve created an array with 6 elements from 0-5, and the goal is to display each element using the foreach loop on the output screen.

// C# foreach loop program to illustrate the working of the loop

using System;

class loopworks

{

static public void Main()

{

Console.WriteLine("Print array:"); //displays text on output window

int[] arr_array = new int[] { 0, 1, 2, 3, 4, 5, }; // array creation

// foreach loop begins and runs till last item

foreach(int i in arr_array)

{

Console.WriteLine(i);

}

} // end of code

Output

C_Sharp_foreach_2.

For understanding the code better, here’s an equivalent for loop code for the same goal.

for(int i = 0; i < arr_array.Length; i++)

{

Console.WriteLine(arr_array[i]);

}

Replacing this code with the foreach loop code in the above program will give the same output.

Example Codes of C# Foreach

Use foreach to Find a Char in a String

Foreach can also be used to check whether a certain character is present in a given string.

using System;

class loopworkseg1

{

static public void Main()

{

//reading the string

string s = "Zahwah Jameel";

//converting string to array with characters as items

char[] chArray = s.ToCharArray();

foreach (char ch in chArray)

{

if (ch.ToString() != " ")

Console.WriteLine(ch);

}

Output:

C_Sharp_foreach_3.

Foreach in Collection

The C# foreach loop can be implemented to read the number of occurrences of a certain number or character in the collection. Here’s the sample code:

using System;

class loopworkseg2

{

static public void Main()

{

// Find number of occurrences of a char in a string

string str = "education is free";

char[] chars = str.ToCharArray();

int ecount = 0;

// Loop through chars and find all 'n' and count them

foreach (char ch in chars)

{

if (ch == 'e')

ecount++;

}

Console.WriteLine($"Total e found {ecount}");

}