Control Structures in Practice
Most programming languages with control structures have an initial keyword which indicates the type of control structure involved. Languages then divide as to whether or not control structures have a final keyword.
- No final keyword: Algol 60, C, C++, Haskell, Java, Pascal, Perl, PHP, PL/I, Python, PowerShell. Such languages need some way of grouping statements together:
- Algol 60 and Pascal :
begin...end - C, C++, Java, Perl, PHP, and PowerShell: curly brackets
{...} - PL/1:
DO...END - Python: uses indentation level (see Off-side rule)
- Haskell: either indentation level or curly brackets can be used, and they can be freely mixed
- Algol 60 and Pascal :
- Final keyword: Ada, Algol 68, Modula-2, Fortran 77, Mythryl, Visual Basic. The forms of the final keyword vary:
- Ada: final keyword is
end+ space + initial keyword e.g.if...end if,loop...end loop - Algol 68, Mythryl: initial keyword spelled backwards e.g.
if...fi,case...esac - Fortran 77: final keyword is
end+ initial keyword e.g.IF...ENDIF,DO...ENDDO - Modula-2: same final keyword
ENDfor everything - Visual Basic: every control structure has its own keyword.
If...End If;For...Next;Do...Loop;While...Wend
- Ada: final keyword is
Read more about this topic: Control Flow
Famous quotes containing the words control, structures and/or practice:
“The mind is the greatest of all human forces. Control the mind and you control the body.”
—Griffin Jay, Randall Faye, and Lew Landers. Armand Tesla (Bela Lugosi)
“It is clear that all verbal structures with meaning are verbal imitations of that elusive psychological and physiological process known as thought, a process stumbling through emotional entanglements, sudden irrational convictions, involuntary gleams of insight, rationalized prejudices, and blocks of panic and inertia, finally to reach a completely incommunicable intuition.”
—Northrop Frye (b. 1912)
“As an example of just how useless these philosophers are for any practice in life there is Socrates himself, the one and only wise man, according to the Delphic Oracle. Whenever he tried to do anything in public he had to break off amid general laughter. While he was philosophizing about clouds and ideas, measuring a flea’s foot and marveling at a midge’s humming, he learned nothing about the affairs of ordinary life.”
—Desiderius Erasmus (c. 1466–1536)