Loops are a type of control flow structure in programming in which a series of statements may be executed repeatedly until some condition is met.

A loop is a fundamental programming idea that is commonly used in writing programs. They pop up in SharePoint in a number of ways:

  • When writing workflows
  • When writing server-side (SSOM) or client-side (CCOM, JSOM, REST) code
  • When writing apps, or other features requiring programming

Types

A loop can be categorized in two different ways,

1. Entry Controlled Loops

A loop which checks for the condition before the iteration is known as Entry Controlled loops - for example

  • while loop - iterates while a certain condition is true
  • until loop - iterates while a certain condition is false
  • for loop - iterates through numbers in a certain range. Note: not the same as C++ for loop
  • foreach loop - iterates through the elements of a collections.

2. Exit Controlled Loops

A loop which checks the condition after the iteration is knows as Exit Controlled loop - for example

  • do-while loop - iterates while a certain condition is true (the first iteration will run regardless of the condition)
  • do-until loop - iterates while a certain condition is false (the first iteration will run regardless of the condition)

Most languages provide only a subset of loop types described above. For example: in Python there are only foreach (keyword for) and while loops.

Break and continue

In some languages, there are two keywords that simplify the task of implementing a more advanced control flow: break and continue. The former allows you to jump to the operator immediately after the loop, the latter allows you to jump to the end of the current iteration.

Example: implementation of do-until loop in Python using the break keyword:

while True:
    // loop body
    if condition:
        break

Tag usage

The tag can be used for programming related problems in implementing loops feature of any programming language. Please avoid theoretical questions related to tag . See also:

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