Net. Framework - 4.0 [updated]

.NET 4.0 introduced System.Diagnostics.Contracts , allowing design-by-contract programming. Developers could specify preconditions, postconditions, and invariants statically checked by a runtime analyzer—improving reliability, especially in safety-critical systems.

The BCL grew significantly, adding namespaces such as System.Numerics (for BigInteger and complex numbers), System.Threading.Tasks , and System.Runtime.Caching . These additions shifted routine operations from third-party libraries into the core framework, improving consistency and security. net. framework 4.0

// Starting a task Task<int> task = Task.Factory.StartNew(() => { int sum = 0; for (int i = 0; i < 1000; i++) sum += i; return sum; }); .NET 4.0 introduced System.Diagnostics.Contracts