The for Loop

The for loop is used to repeat a block of code a specific number of times. It is especially useful when the number of iterations is known in advance or when you need to iterate over a collection.

General syntax of the for loop

The for loop consists of three main parts:

initialization - usually used to declare and initialize the loop counter.
condition - checked before each iteration. If the condition is true, the loop body is executed. If false, the loop ends.
iteration - executed after each iteration of the loop. Usually used to change the counter value.


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for (initialization; condition; iteration)
{
    // Code that will be executed on each iteration
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Example of using the for loop


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for (int i = 0; i < 5; i++)
{
    Console.WriteLine("Value of i: " + i);
}
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Description:

Initialization: int i = 0 — variable i is declared and set to 0.
Condition: i < 5 — the loop continues while i is less than 5.
Iteration: i++ — increases the value of i by 1 after each iteration.
Loop body: Console.WriteLine("Value of i: " + i); — prints the current value of i.

Iterating over array elements

The for loop is often used to iterate over array elements


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string[] fruits = new string[] { "apple", "banana", "cherry" };
for (int i = 0; i < fruits.Length; i++) // fruits.Length - number of elements in the array
{
    var fruit = fruits[i];
    Console.WriteLine(fruit);
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Using the break operator

The break operator completely stops the loop. It is useful when you need to finish the loop early.


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for (int i = 0; i < 10; i++)
{
    if (i == 5)
        break;
    Console.WriteLine("i: " + i);
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Using the continue operator

The continue operator skips the rest of the current iteration and moves to the next one


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for (int i = 0; i < 5; i++)
{
    if (i == 2)
        continue;
    Console.WriteLine("i: " + i);
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Exercises

Print only even numbers that are less than 10. A number is even if the remainder when divided by 2 equals 0: i % 2 == 0.


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for (int i = 0; i < 10; i++)
{
    // Your code
}
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Given the array int[] numbers = new int[] { 1, 2, 3, -1, 4, 5 };. Print it, but if an element is less than 0, print an error message and stop the loop early.


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int[] numbers = new int[] { 1, 2, 3, -1, 4, 5 };
// Your code
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