Difference between Areay and ArrayList

Question

Difference between Areay and ArrayList in DotnetFramework

Baibhav Kumar · Answer

Array Fixed size: Once you create an array, you can't change its size. Stores a specific data type (like int[], string[], etc.). Faster because it's type-safe. ArrayList Resizable: You can add or remove items anytime. Stores any type of data, but all items are treated as objects, so you may need to convert (cast) them back to their original type. Slower than arrays if you're storing specific types (like only int ) because of type conversions.

Sarthak Varshney · Answer

Feature Array ArrayList Namespace System System.Collections Type Safety Strongly typed (e.g., int[] , string[] ) Not type-safe (stores objects of type object ) Generic Support No (fixed type, but not generic) No (use List for generics) Resizing Fixed size (must know size at creation) Dynamically resizable Performance Faster due to type safety and no boxing/unboxing Slower due to boxing/unboxing of value types Boxing/Unboxing Not required (e.g., int[] stores actual ints) Required for value types (e.g., int is boxed to object ) Indexing Supported Supported Use Case When size is known and type safety is important When size is dynamic but generic List is not used Example: Array: int[] numbers = new int[3]; numbers[0] = 1; ArrayList: ArrayList list = new ArrayList(); list.Add(1); // Value type (int) will be boxed list.Add("hello"); // Stores different types (not type-safe) Recommendation: Use Array for performance-critical, fixed-size, type-safe scenarios. Use List (from System.Collections.Generic ) instead of ArrayList in modern .NET for better type safety and performance. Let me know if you want a comparison including List too!

Difference between Areay and ArrayList

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