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What Is a Self-Modifying Code?

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  • Written By: Alex Newth
  • Edited By: Angela B.
  • Last Modified Date: 04 September 2016
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    Conjecture Corporation
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Self-modifying code is a programming philosophy in which the developer makes a program that is able to alter its own coding when executed. While the developer can enter parameters for the self-modifying code, it usually changes and optimizes itself without interaction. There are some computer phenomena that cause coding to change unintentionally, but only intentional self-modifying code truly is considered self-modifying. This most commonly is used by developers to improve their coding, because running the coding many times can greatly improve the original design.

The most defining aspect of self-modifying code is its ability to change itself for the better. This can only be done when the coding is getting ready to execute and when it is preparing to run. The executing code will have to take stock of the computer’s current software, state and other factors, so this normally helps the code recognize processing errors to best correct its own processing.

Developers sometimes set parameters for self-modifying code, such as correcting itself mostly for performance, but the code normally will correct itself without interaction or prompting. Aside from increased processing, the code also will erase unneeded code that is just dragging down the program and it will decrease path lengths. At the same time, developers can specify areas that cannot be changed, because altering some parts of the code may cause the entire program to suffer or stop working.

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A phenomenon occasionally occurs in software in which the coding changes without the developer writing in any instructions for it to do so. This normally occurs with software rot or buffer problems and, while the coding is being changed, it is not considered self-modifying code. There are two reasons for this, one being that the change is not intentionally made by the developer. The second reason is that self-modifying programming is meant to improve coding, while buffer and rot issues degrade coding.

There are many benefits to having self-modifying code, because it constantly will work to improve itself based on the computer’s current state and other internal factors. This is most rigorously used by the developer before the code is sold or distributed. By allowing the code to run constantly, it enables the programming to fix itself and any errors or problems that are caused by the developer during the coding’s creation. Another use for this is in computers with limited memory, because this code will respond to a memory shortage by reducing its own size.

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