C# Loops Explained

Loop

A loop is a programming structure that repeats a sequence of instructions until a specific condition is met. Loops are used very often, that's why you must be comfortable with them.

An example of a loop is a while loop, which states that "while a condition is valid, keep looping". There are other loops in C# as well, as do while, for, and foreach.

Syntax

while (condition) 
{
    // Do something
}

While Loop Example

int i = 0;
int goal = 7;

while (i < goal)
{
    Console.Writeline("We didn't get there yet!");
    i++;
}

This block of code would write "We didn't get there yet!" exactly 7 times.

Foor Loop Example

          for (var i = 0; i < 7; i++)
            {
                Console.WriteLine($"Current Index is {i}");
            }

            /*
             * Output
             * Current Index is 0
             * Current Index is 1
             * Current Index is 2
             * Current Index is 3
             * Current Index is 4
             * Current Index is 5
             * Current Index is 6
             */

Foreach loop

            var names = new List<string> {"Lukasz", "Jan", "John", "Jane", "Monica"};

            foreach (var name in names)
            {
                Console.WriteLine($"How you doin', {name}");
            }

            /*
             * Output
             * How you doin' Lukasz
             * How you doin' Jan
             * How you doin' John
             * How you doin' Jane
             * How you doin' Monica
             */

And the last one is the do while loop

            var knowledgeLevel = 0;
            var knowledgeRequired = 1000;

            do
            {
                Console.WriteLine("Keep studying!");
                knowledgeLevel++;
            } while (knowledgeLevel < knowledgeRequired);

However...

There's one more looping mechanism that you can use. List class has it's own "ForEach" method.

            var names = new List<string> {"Lukasz", "Jan", "John", "Jane", "Monica"};

            names.ForEach(name => Console.WriteLine($"How you doin', {name}"));

            /*
             * Output
             * How you doin' Lukasz
             * How you doin' Jan
             * How you doin' John
             * How you doin' Jane
             * How you doin' Monica
             */

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Comments

[erica (she/her)]

I didn't know about the loop on the list class, and I use loops almost every day! Great post!

[Łukasz Reszke]

Thanks, Erica :)