The structure of a for loop is as follow:

for (initializer; condition; iterator)
{
    body
}

The body of the for loop is executed when the condition evaluates to true.

A for loop consists of main 3 parts:

1. initializer
2. condition
3. iterator

(Docs, 2018)

initializer

The statements in the initializer section are executed first and executed only once before entering the loop.

This is usually where a local loop variable is declared and initialized.

condition

The condition section is a Boolean expression which is evaluated before every iteration.

The for loop will stop executing when it evaluates to false.

iterator

The statements in the iterator section are executed after each iteration.

This is usually where the loop variable is incremented or decremented.

Example

The same example used in while and do…while loop can be written using for loop, which is more concise:

for (int x = 10; x < 20; x++)
{
    Console.WriteLine($"Value of x: {x}");
}

Output:

Value of x: 10
Value of x: 11
Value of x: 12
Value of x: 13
Value of x: 14
Value of x: 15
Value of x: 16
Value of x: 17
Value of x: 18
Value of x: 19

In this case,

Initializer	Condition	Iterator
int x = 10	x < 20	x++

Live-code example

References

1. Docs, M. (2018, June 13). for (C# reference). Retrieved from https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/for