What is the difference between foreach and LINQ query (from .. in ..) in C#?
Mariusz Postol
The main difference between foreach and LINQ is that foreach is used for simple iteration, while LINQ is used for querying and manipulating data. LINQ queries are more expressive and can be used to perform complex operations on collections, such as filtering, sorting, and projecting data.
My point is that foreach is a typical statement implementing iteration against all entities fetched from the selected data source. The data source must implement IEnumerable. the from .. in.. clause is an expression that:
foreach
from .. in..
The main consequence is that foreach requires all data to be fetched from the data source to the in-process memory, causing an overload.
To recognize something as a simple iteration each engineer including but not limited to software developers need simplicity metrics, which allows us to compare and resolve a binary condition `if (something is simpler) then ....`. I am expecting an answer like this "Use LINQ query (`from .. in ..`) because it is impossible to use `foreach` in the case of ..... to provide constructive guidance to software developers.
From the language point of view, we can recognize `foreach ....` as instruction and LINQ query (`from .. in ..`) as expression.