What is the role of the Program.cs file in a .NET Core

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Accepted Answer

The Program.cs file in .NET Core serves as the entry point and main configuration file for the application. It replaces the traditional Global.asax and Startup.cs combination from earlier versions and follows a simplified, top-level statement approach in newer versions.

Role and Responsibilities:

1. Application Entry Point:
- Contains the Main method (or top-level statements)
- First code executed when application starts
- Controls application lifecycle

2. Host Configuration:
- Creates and configures the application host (IHostBuilder or WebApplicationBuilder)
- Sets up hosting environment, configuration, and logging
- Defines application startup behavior

3. Service Configuration:
- Registers services with dependency injection container
- Configures application dependencies
- Sets up middleware pipeline

4. Application Startup:
- Builds and runs the application host
- Starts listening for HTTP requests (in web applications)
- Manages application lifetime

In .NET 6+ with Minimal APIs:
- Uses top-level statements for concise syntax
- All configuration happens in a single file
- No explicit Main method required
- Simplified startup code

The Program.cs file is the central configuration point that defines how the .NET Core application is built, configured, and executed.