C# foreach Loop

The foreach loop in C# iterates through the collection of items it may be an array or a list, it executes the block of code on a collection of items when executing forloop it pass through items in the collection and finally it displays one by one.

Syntax:

foreach(dataType variableName in collection variable)
{
// codeblock
}

In the above syntax variableName holds the current element in the collection, collection variables define the data structure which implements the interface IEnumerable it having the collection of list items to be iterated and displayed one by one. The codeBlock contains the logic which is to be executed in a loop.

Flowchart

Let’s see the flow of the foreach looping process,

How C# foreach Loop works?

The working process of the foreach loop is that it iterates through the elements in the collection while using the foreach loop it is mandatory to enclose statements in curly braces {}. When declaring a variable of loop counter variable we can declare the same type as the base type of array.

Example:

foreach(int items in arrayValues)
{
Console.WriteLine(items);
}

The keyword is used in a foreach loop to iterate the item, the keyword selects the item from iteration on each time and it stores in the variable element. In the first iteration, the starting item of iteration is stored in an element and on the second iteration, the next element will be selected and so on. The foreach loop will be executed equally to the number of elements in the array or list.

Let’s see the difference between for loop and foreach loop as follows,

• foreach loop executes the block of statements until every element present in the array, whereas for loop executes a block of statements until the given condition becomes false.
• In the foreach loop, it iterates an array only in the forward direction, but in for loop, it iterates both forward and backward directions.
• In the variable declaration, foreach has five types whereas for loop has three type declarations.0

In the foreach loop, you can also see the coding snippets in which we can stop and exit a loop with the help of using the goto, return, break, and throw statements. Let’s see the example in which the code will quit the execution once the number equals to 12.

using System;
class Program
{
static void Main(string[] args)
{
Console.WriteLine("foreach loop Sample!");
int[] oddArray = new int[] { 2,4,6,8,10,12,14,16,18,20 };
// Loop through array items
foreach (int num in oddArray)
{
Console.WriteLine(num);
// it don't read the number after 12
if (num == 12) break;
}
Console.ReadKey();
}
}

Another example in forloop, if you need to find a character in string we can go with foreach loop for this to verify one character at a time in a string, it creates an array of characters from a string and read only one character at a time it also ensures that the whitespace between characters is omitted.

// Reads one character at a time and it skips the process if space comes
string data = "C# Programming";
// it convert the string into an array of chars
char[] _array = data .ToCharArray();
// display one char at a time
foreach (char item in _array)
{
if (item.ToString() != " ")
Console.WriteLine(item);
}

It shows that the use of foreach loop for collection in a string it finds the number of occurrence of a character in a string,

string _string = "Latest C# Programming :Language";
char[] _charArray = _string.ToCharArray();
int _count = 0;
// Loop through chars and find all 'n' and count them
foreach (char item in charArray )
{
if (item  == 'a')
_count++;
}
Console.WriteLine($"Total n found {_count}");

In this example using a foreach loop, it creates an array of string that reads and displays each and every string one at a time.

// Array of  name list in string
string[] nameList = new string[]
{ "Chand", "Leo", "Smith", "Allen", "Rick" };
// Loop through array and read all authors
foreach (string item in nameList )
{
Console.WriteLine(item );
}

Examples of C# foreach Loop

Let’s see program samples for the foreach loop, the following program using the foreach loop to show the iteration through the array elements.

Program #1

Code:

using System;
class Program_1
{
// Main Method
public static void Main(string[] args)
{
Console.WriteLine("Display Elements");
// creating an array
char[] _arrayList={'L','O','O','P','I','N','G'};
// it execute the loop till the last appearance of element in the array
foreach(char items in _arrayList)
{
Console.WriteLine(items);
}
}
}

Output:

Program #2

Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace Program_2
{
class Program_2
{
static void Main(string[] args)
{
string[] data = new string[5]; // declaring array
//Storing value in array element
data[0] = "Java";
data[1] = "DotNet";
data[2] = "PHP";
data[3] = "SQL SERVER";
data[4] = "ANDROID";
//retrieving value using foreach loop
foreach (string items in data)
{
Console.WriteLine("Welcome " + items);
}
//Console.ReadLine();
}
}
}

Output:

As the above example foreach with the array, we can use a loop with a list object to access the elements in a list object. Let’s see the following example using the foreach loop to iterate through a list element.

Program #3

Code:

using System;
using System.Collections.Generic;
namespace Program_3
{
class Program_3
{
static void Main(string[] args)
{
List<string> nameList = new List<string>() { "Smith", "Steve", "Gates" };
foreach (string name in name list)
{
Console.WriteLine(name);
}
Console.WriteLine("Press Enter Key to Exit..");
}
}
}

Output:

Program #4

Code:

using System;
class Program_4
{
// Main Method
public static void Main(String[] arg)
{
{
int[] codes = { 135, 142, 75, 106, 100 };
int newCodes = HighestCodes(codes);
Console.WriteLine("New Code is " + newCodes);
}
}
// method to find HighestCodes
public static int HighestCodes(int[] values)
{
int _num = values[0];
// for each loop
foreach (int item in values)
{
if (item > _num)
{
_num = item;
}
}
return _num;
}
}

Output:

Conclusion

At the end of this article, you have learned about how the foreach loop working and how to access value from a collection of the array and also we analyzed syntax, flowchart for easy understanding. I hope you have understood the article on looping.

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