Editing Source code (section)

===Modification===
{{see also|Software development|Software maintenance}}
Access to the source code (not just the [[object code]]) is essential to modifying it.{{sfn|Katyal|2019|p=1195}} Understanding existing code is necessary to understand how it works{{sfn|Katyal|2019|p=1195}} and before modifying it.<ref name=Offutt>{{cite web |last1=Offutt |first1=Jeff |author1-link=Jeff Offutt |title=Overview of Software Maintenance and Evolution |url=https://cs.gmu.edu/~offutt/classes/437/maintessays/maintEvolutionOverview.html |website=[[George Mason University]] Department of Computer Science |access-date=5 May 2024 |date=January 2018}}</ref> The rate of understanding depends both on the code base as well as the skill of the programmer.{{sfn|Tripathy |Naik|2014|p=296}} Experienced programmers have an easier time understanding what the code does at a high level.{{sfn|Tripathy |Naik|2014|p=297}}  [[Software visualization]] is sometimes used to speed up this process.{{sfn|Tripathy |Naik|2014|pp=318-319}} 

Many software programmers use an [[integrated development environment]] (IDE) to improve their productivity. IDEs typically have several features built in, including a [[source-code editor]] that can alert the programmer to common errors.{{sfn|O'Regan|2022|p=375}}  Modification often includes [[code refactoring]] (improving the structure without changing functionality) and restructuring (improving structure and functionality at the same time).{{Sfn|Tripathy |Naik|2014|p=94}} Nearly every change to code will introduce new bugs or unexpected [[ripple effect]]s, which require another round of fixes.<ref name=Offutt/> 

[[Code review]]s by other developers are often used to scrutinize new code added to a project.{{sfn|Dooley|2017|p=272}} The purpose of this phase is often to verify that the code meets style and [[maintainability]] standards and that it is a correct implementation of the [[software design]].{{sfn|O'Regan|2022|pp=18, 21}} According to some estimates, code review dramatically reduce the number of bugs persisting after [[software testing]] is complete.{{sfn|Dooley|2017|p=272}} Along with software testing that works by executing the code, [[static program analysis]] uses automated tools to detect problems with the source code. Many IDEs support code analysis tools, which might provide metrics on the clarity and maintainability of the code.{{sfn|O'Regan|2022|p=133}} [[Debuggers]] are tools that often enable programmers to step through execution while keeping track of which source code corresponds to each change of state.{{sfn|Kaczmarek ''et al.''|2018|pp=348-349}}