freeCodeCamp/guide/english/csharp/for-loop/index.md

title
For Loop

For Loop

The for loop executes a block of code repeatedly until a specified conditional expression evaluates to false.

Anatomy of for loop:

for (initialization; condition; iterator)
{
    body
}

• initialization - The initialization statement(s) sets the initial condition and run only once before you enter the body of the loop.
• condition - Boolean expression which determines whether the body of the loop should execute again or the loop should exit.
• iterator - Executes after each iteration of the body of the loop.

Example 1

for (int i = 0; i < 5; i++)
{
    Console.WriteLine("Number " + i);
}

Output:

> Number 0
> Number 1
> Number 2
> Number 3
> Number 4

• Only counts to 4 due to the fact that the initial number is 0 meaning that 5 numbers including 0 would reach 4.

Example 2

int j = 0;
for (int i = 0; j < 5; i++)
{
    Console.WriteLine("Numbers {0} {1}", i, j);
    j++;
}

Output:

> Numbers 0 0
> Numbers 1 1
> Numbers 2 2
> Numbers 3 3
> Numbers 4 4

Example 3 - Simplification of Example 2

for (int i = 0, j = 0; i < 5 && j < 5; i++, j++)
{
    Console.WriteLine("Numbers {0} {1}", i, j);
}

Output:

> Numbers 0 0
> Numbers 1 1
> Numbers 2 2
> Numbers 3 3
> Numbers 4 4

Example 4

for (int i = 5; i > 0; i--)
{
    Console.WriteLine("Number " + i);
}

Output:

> Number 5
> Number 4
> Number 3
> Number 2
> Number 1

Example 5

// Infinite loop - The loop body is executed infinitely
for (; ;)
{
    Console.WriteLine("The universe is infinite");
}

// Anything after infinite loop is reported as "Unreachable code detected" in Visual Studio
Console.WriteLine("Never considered for execution");

Output:

> The universe is infinite
> The universe is infinite
> The universe is infinite
> ....
> ....

Example 6

int i = 0;
for (; i < 5;)
{
    Console.WriteLine("Number " + i);
    i++;
}

Output:

> Number 0
> Number 1
> Number 2
> Number 3
> Number 4

Other Resources

• Microsoft Documentation

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