?? Understanding Compile Time vs. Run Time in .NET ??

If you're developing APIs or any .NET application, you've probably come across terms like compile time and run time. But what do they really mean, and how do they impact your code? ??

Here's a simple breakdown:

?? Compile Time

This happens before your application runs. During compile time, the code you write in C#, for example, is converted into machine code by the compiler. This is the phase where:

The compiler checks for syntax errors, type mismatches, and other issues.

Your code is transformed into an executable format that can be run later.

Example: When you define a const field, its value is fixed at compile time, meaning the compiler embeds it directly into the executable.

?? Run Time

Once your application or API is deployed and starts executing, you're in the run-time phase. This is where:

The compiled code runs, interacting with users, APIs, databases, and more.

The logic you’ve written is actively processed and errors (like null references) may occur if the program encounters unexpected inputs or conditions.

Example: When you use static readonly fields, their values are set at run time. This allows for more flexibility but means the value is initialized only when the application starts running.

?? Key Difference:

Compile time is about building and preparing your code before it runs.

Run time is the phase when the application is actually executing and processing data.

Understanding this distinction can help you write better, more optimized code. For example, using const when possible can improve performance since values are fixed and determined at compile time. ?

?? Tip: Whenever possible, prefer const over static readonly if the value can be determined at compile time to improve performance!