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How does code work?

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There are 1000 page textbooks that address this question, so this is an extremely high level overview.

When we write code, we are essentially creating a set of instructions for a computer to execute. The computer executes these instructions using its hardware components, such as the CPU, memory, and storage devices.

Here's a simplified explanation of how code works within a computer:

  1. Writing code: The first step is to write the code using a programming language. This code is stored in a file on the computer's hard drive.
  2. Compilation/Interpretation: Depending on the programming language used, the code is either compiled or interpreted. Compilation involves converting the code into machine language, which is the language that the computer's CPU can execute directly. Interpreted languages are executed directly by an interpreter program without being compiled.
  3. Execution: Once the code is compiled or interpreted, it is ready for execution. The CPU reads the instructions one by one from memory and executes them. These instructions might include arithmetic operations, comparisons, conditional statements, loops, and function calls.
  4. Memory management: As the code executes, it may need to store and retrieve data in memory. The computer's memory is organized into various data structures, such as arrays, linked lists, and trees. The code must manage memory carefully to avoid memory leaks, where memory is allocated but not properly released when it is no longer needed.
  5. Input and output: Code often needs to interact with the outside world by receiving input and producing output. Input might come from a keyboard, mouse, or other input device, while output might be displayed on a screen, printed on paper, or sent over a network connection.
  6. Error handling: Code must be prepared to handle errors and exceptions that might occur during execution. These might include invalid inputs, network failures, or memory errors. Code can use techniques such as exception handling and error codes to detect and recover from these errors.
  7. Termination: Finally, the code will terminate once it has completed its task or encountered an error. At this point, any resources that were allocated during execution must be released, and any output must be finalized and saved.