Dfference between an Array and ArrayList in dotnet framework

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Difference between an Array and ArrayList in dotnet framework

Vishal Yelve · Answer

Feature Array ArrayList Type Safety Strongly typed Weakly typed (stores object ) Resizable ? Fixed size ? Automatically resizes Performance Faster (no boxing/unboxing) Slower (boxing/unboxing for value types) Generics Support ? (Use T[] ) ? (Use List instead) Usage Recommendation Use for fixed-size , typed data Use List instead of ArrayList Conceptual Differences ?? 1. Array Declared with a specific type and fixed size . Example: int[] numbers = new int[3]; numbers[0] = 1; numbers[1] = 2; Benefits: Type safety (compile-time checking). Better performance for value types. Limitations: Size is fixed after creation. Can't mix different data types. 2. ArrayList Part of System.Collections (non-generic). Stores elements as object , allowing mixed types (not recommended). Example: ArrayList list = new ArrayList(); list.Add(1); // boxed int list.Add("hello"); // string Drawbacks: Boxing/unboxing overhead with value types. No compile-time type checking. Example Comparison // Array (strongly typed) int[] ages = new int[2]; ages[0] = 25; ages[1] = 30; // ArrayList (weakly typed) ArrayList data = new ArrayList(); data.Add(25); // boxed data.Add("John"); // allowed, but dangerous int age = (int)data[0]; // requires casting Should You Use ArrayList ? No — use List instead (from System.Collections.Generic ). List list = new List (); list.Add(10); // no boxing int num = list[0]; // no casting needed In Summary: Use Case Recommended Type Fixed-size, performance-critical Array Dynamic, type-safe collection List Legacy non-generic collections ArrayList (not recommended)

Sangeetha S · Answer

Feature Array ArrayList Size Fixed Dynamic Type Safety Yes (strongly typed) No (stores object ) Performance Faster (no boxing) Slower (boxing/unboxing) Generic Support No (use List instead) No (use List instead) Use Case Known size, type-safe Mixed types, dynamic size

Dfference between an Array and ArrayList in dotnet framework

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