Editing Control flow (section)

== Control structures in practice ==
Most programming languages with control structures have an initial keyword which indicates the type of control structure involved.{{clarify|date=November 2015}} Languages then divide as to whether or not control structures have a final keyword.

* No final keyword: [[ALGOL 60]], [[C (programming language)|C]], [[C++]], [[Go (programming language)|Go]], [[Haskell]], [[Java (programming language)|Java]], [[Pascal (programming language)|Pascal]], [[Perl]], [[PHP]], [[PL/I]], [[Python (programming language)|Python]], [[PowerShell]]. Such languages need some way of grouping statements together:
** ALGOL 60 and Pascal: <code>begin</code> ... <code>end</code>
** C, C++, Go, Java, Perl, PHP, and PowerShell: [[Curly bracket programming language|curly brackets]] <code>{</code> ... <code>}</code>
** PL/I: <code>DO</code> ... <code>END</code>
** Python: uses [[Indent style|indent]] level (see [[Off-side rule]])
** Haskell: either [[Indent style|indent]] level or curly brackets can be used, and they can be freely mixed
** Lua: uses <code>do</code> ... <code>end</code>
* Final keyword: [[Ada (programming language)|Ada]], [[APL (programming language)|APL]], [[ALGOL 68]], [[Modula-2]], [[Fortran 77]], [[Mythryl]], [[Visual Basic]]. The forms of the final keyword vary:
** Ada: final keyword is <code>end</code> + ''space'' + initial keyword e.g., <code>if</code> ... <code>end if</code>, <code>loop</code> ... <code>end loop</code>
** APL: final keyword is <code>:End</code> optionally + initial keyword, e.g., <code>:If</code> ... <code>:End</code> or <code>:If</code> ... <code>:EndIf</code>, <code>Select</code> ... <code>:End</code> or <code>:Select</code> ... <code>:EndSelect</code>, however, if adding an end condition, the end keyword becomes <code>:Until</code>
** ALGOL 68, Mythryl: initial keyword spelled backwards e.g., <code>if</code> ... <code>fi</code>, <code>case</code> ... <code>esac</code>
** Fortran 77: final keyword is <code>END</code> + initial keyword e.g., <code>IF</code> ... <code>ENDIF</code>, <code>DO</code> ... <code>ENDDO</code>
** Modula-2: same final keyword <code>END</code> for everything
** Visual Basic: every control structure has its own keyword. <code>If</code> ... <code>End If</code>; <code>For</code> ... <code>Next</code>; <code>Do</code> ... <code>Loop</code>; <code>While</code> ... <code>Wend</code>