# Collection Expression

*noun*

say it: **“kuh-LEK-shun ek-SPRESH-un”** **/kəˈlɛkʃən ɪkˈsprɛʃən/**

Square brackets around a list of values that create an array or list in one step, such as \[1, 2, 3\].

## What is **Collection Expression** in C#?

**Collection Expression** — Square brackets around a list of values that create an array or a list in one step. The variable's type decides which one you get, and `[]` makes an empty one.

```csharp
decimal[] prices = [12.75m, 10.25m, 8.50m];
List<string> genres = ["Mystery", "Sci-Fi"];
List<string> wishlist = [];
Console.WriteLine(prices.Length); // 3
```

## In a sentence

- “I filled the prices array with a **collection expression**: \[12.75m, 10.25m\].”

Level: Apprentice · [More C# terms at this level](https://www.ask-codey.com/glossary?category=c-sharp&level=2)

Updated: October 28, 2026

Source: https://www.ask-codey.com/glossary/collection-expression