which loop runs faster – for loop or foreach?

  • A for-loop is a simple looping control statement in the C# language, which can be used to iterate over indexed data structures - such as Arrays.
  • A foreach-loop is a looping control statement which can be used to iterate over a collection that derives from the IEnumerable interface - that provides the Enumerator.
  • Conceptually, looping over an indexed data structure is faster than looping over a collection using an Enumerator - because the for-loop is simply picking up the values inside the indexes and this is equivalent to picking the value from a memory location - simple and straight forward.
  • A for-loop statement can't run on data-structures that are not indexed - such as Dictionaries.
  • A foreach-loop statement internally calls on the Enumerator and seeks through the collection, which has a slight overhead. There is an overhead for initializing the Enumerator for the collection, which is not required in a traditional for-loop.
  • But a foreach-loop has a cleaner and intuitive syntax when compared with the for-loop syntax and is generally preferred for iterating over most of the collections types.
  • A for-loop is a simple looping control statement in the C# language, which can be used to iterate over indexed data structures – such as Arrays.
  • A foreach-loop is a looping control statement which can be used to iterate over a collection that derives from the IEnumerable interface – that provides the Enumerator.
  • Conceptually, looping over an indexed data structure is faster than looping over a collection using an Enumerator – because the for-loop is simply picking up the values inside the indexes and this is equivalent to picking the value from a memory location – simple and straight forward.
  • A for-loop statement can’t run on data-structures that are not indexed – such as Dictionaries.
  • A foreach-loop statement internally calls on the Enumerator and seeks through the collection, which has a slight overhead. There is an overhead for initializing the Enumerator for the collection, which is not required in a traditional for-loop.
  • But a foreach-loop has a cleaner and intuitive syntax when compared with the for-loop syntax and is generally preferred for iterating over most of the collections types.
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Sriram Mannava

I'm a full-stack developer and a software enthusiast who likes to play around with cloud and tech stack out of curiosity.

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