# The foreach loop in C#

# Loops in C#:
---
## Introduction :
* There are multiple ways to writing the loops in `C#` the most basics loops in any programming languages are `for` and `while` loop. In `C#` we have another type of advance loop that is the `foreach` loop. We will see the `syntax` and execution of the `foreach` loop below.

* Before we talk about the advanced `foreach` loop let me just give a brief explanation of the other looping condition.

### Types of Loops :
Loops | When to use the Loop
----|----
`for`| We can use this loop whenever we know the starting and ending conditions.
`while` | We can use this loop whenever we don't know the starting condition but we know the end condition.
`do-while`| We can use this loop whenever we want to execute the loop at least one time before it checks the condition.
`foreach` | We can use this advanced for loop in concepts like Array and other data structure concepts where we don't want to use the index number to access the elements or Some of the data structure they don't have the index concept.

## `foreach` loop :
* `foreach` is advanced `for` loop which can be used to access the element of the collection without using indexes.

### Syntax :
```cs
foreach(data_type var_name in collection_var) {
    //statements
}
```
### Understanding the `foreach` loop :
```cs
using System;
// Topic: foreach
class MainClass {
  public static void Main (string[] args) 
  {
    int[] num = {1,2,3,4,5};
    Console.WriteLine("Using the for loop");
    //for loop
    for(int i=0;i<num.Length;i++)
    {
      Console.WriteLine(num[i]);
    }

    Console.WriteLine("Using the foreach loop");
    //foreach loop
    foreach(int a in num)
    {
      Console.WriteLine(a);
    }
  }
}
```
Output :
```cs
Using the for loop
1
2
3
4
5
Using the foreach loop
1
2
3
4
5
```
## Explanation :
### `for` loop :
* In the above code, you can see using the `for` loop we need to access the elements using the index value. Here using the `for` loop we need to keep the index values in check that is if the index values are in the range of the given collection/array length or else this will lead to the `System.IndexOutOfRangeException`. And also, we need to increment/decrement the index value as per our required outputs.

### `foreach` loop :
* Like `for` loop this doesn't use any kind of index to retrieve elements from the array. This advanced `foreach` loop will take the array and retrieve the elements one by one until the array will not have any elements left. This happens because if the array has elements then the `foreach` loop returns `true` else it will return `false` and stop the execution.