For loops

There’s another type of loop called a for loop.

You may ask: “why do we need another type of loop? Isn’t a while loop enough?”
The answer is… yes. A while loop can do absolutely everything a for loop can do.

So why do we use a for loop? Convenience. You’ll grow to like for loops, I promise :)

Basic syntax

In C#, we can write a for loop like this:

for (initialization; condition; update) {
    // Code to repeat
}

This looks much more complicated than a while loop, partly because it is. However, this becomes much simpler if you realise that the code above is exactly the same as this while loop:

initialization;
while (condition) {
    // Code to repeat
    update;
}

All that a for loop does is run the code in initialization once at the start, then run the code in update at the end of each loop iteration.

The second part - the condition - is exactly the same as in a while loop.

The fact that the two code snippets above are equivalent is very useful - it makes for loops much easier to understand!

Our example from before: counting to 5

If you don’t remember the code from the while loops chapter, here it is again:

int count = 1;
while (count <= 5) {
    Console.WriteLine(count);
    count++; // Increment count by 1
}

This looks very similar to our syntax for how a for loop works, right?

• int count = 1 is our initialization
• count <= 5 is our condition
• count++ is our update

So, we can essentially substitute those parts into our for loop syntax:

for (int count = 1; count <= 5; count++) {
    Console.WriteLine(count);
}

And… there we are! That’s a for loop that counts from 1 to 5.

Output:

1
2
3
4
5

Changing the values of a for loop

With a for loop, you can easily change the range of the loop just by changing the values in the initialization, condition, and update sections.

For example, to count from 0 to 10, you could write:

for (int count = 0; count <= 10; count++) {
    Console.WriteLine(count);
}

If we then wanted to count up in 2s instead of 1s, we could change the update part:

for (int count = 0; count <= 10; count += 2) {
    Console.WriteLine(count);
}

(remember that the count++ we had before just meant count += 1, or count = count + 1)

We can even count backwards! To count from 5 down to 1, we could write:

for (int count = 5; count >= 1; count--) {
    Console.WriteLine(count);
}

• We start the count at 5
• We keep looping as long as count is greater than or equal to 1
• We decrease count by 1 each time through the loop

Don’t know how to use for loops yet? Use while loops!

As I mentioned earlier, for loops are just a while loop dressed up in fancy clothes.

You can use a while loop for any task, it’s just much neater to use a for loop when you know in advance how many times you want to repeat something.