# For..in Iteration The `for..in` loop is the modern way to iterate over collections in DWScript. It is more readable than standard range loops and automatically handles the underlying iteration logic. ## Arrays Iterating over a dynamic or static array returns each element in order. ```pascal var fruits := ['Apple', 'Banana', 'Cherry']; for var fruit in fruits do PrintLn(fruit); // OUTPUT // Apple // Banana // Cherry ``` ## Sets When iterating over a set, elements are returned in their **ordinal order** (the order defined in the enumeration), regardless of the order they were added to the set. ```pascal type TDays = (Mon, Tue, Wed, Thu, Fri, Sat, Sun); var weekend: set of TDays := [Sun, Sat]; for var day in weekend do PrintLn(day.Name); // OUTPUT // Sat // Sun ``` ## Strings Iterating over a string returns each **full Unicode codepoint**. Note that the loop variable `c` is of type **String** (containing the full character, which may be a surrogate pair), not `Char`. ```pascal var msg := 'Ready 🚀'; for var c in msg do Print(c + '|'); // OUTPUT // R|e|a|d|y| |🚀| ``` This correctly handles multi-byte characters like emojis, treating them as a single logical unit. ## Ranges You can iterate over numeric ranges directly using the bracketed range syntax. ```pascal for var i in [1..5] do Print(i.ToString + ' '); // OUTPUT // 1 2 3 4 5 ``` ## Type Enumerations You can iterate over an entire enumeration type to visit all possible values. ```pascal type TColor = (Red, Green, Blue); for var c in TColor do PrintLn(c.Name); // OUTPUT // Red // Green // Blue ``` ## Associative Arrays (Dictionaries) Direct iteration over an associative array is **not supported**. This is an intentional design choice to avoid ambiguity; iterating directly would yield key-value tuples, whereas most users only need the keys or the values. Forcing the use of `.Keys` makes the code's intent explicit. ```pascal var data: array [String] of Integer; data['A'] := 10; data['B'] := 20; // Explicitly iterate over keys var keys := data.Keys; keys.Sort; for var k in keys do PrintLn(k + ': ' + data[k].ToString); // OUTPUT // A: 10 // B: 20 ``` :::info For standard numeric range loops (e.g. `1 to 10`), see **[Basic Loops](/lang/control_flow/loops)**. :::

For..in Iteration

The for..in loop is the modern way to iterate over collections in DWScript. It is more readable than standard range loops and automatically handles the underlying iteration logic.

Arrays

Iterating over a dynamic or static array returns each element in order.

Sets

When iterating over a set, elements are returned in their ordinal order (the order defined in the enumeration), regardless of the order they were added to the set.

Strings

Iterating over a string returns each full Unicode codepoint. Note that the loop variable c is of type String (containing the full character, which may be a surrogate pair), not Char.

This correctly handles multi-byte characters like emojis, treating them as a single logical unit.

Ranges

You can iterate over numeric ranges directly using the bracketed range syntax.

Type Enumerations

You can iterate over an entire enumeration type to visit all possible values.

Associative Arrays (Dictionaries)

Direct iteration over an associative array is not supported. This is an intentional design choice to avoid ambiguity; iterating directly would yield key-value tuples, whereas most users only need the keys or the values. Forcing the use of .Keys makes the code's intent explicit.