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:
“Above and beyond paying attention to feelings before and after a separation, never threaten your child with leaving or loss of love in an effort to control her behavior. Children believe their parents’ assertions that “I will send you away,” “I won’t love you any more,” “I’ll go away,” and are terrified with good reason. Fear is a very poor way of disciplining a child, and it can cause severe lifelong anxiety.”
—Alicia F. Lieberman (20th century)
“The philosopher believes that the value of his philosophy lies in its totality, in its structure: posterity discovers it in the stones with which he built and with which other structures are subsequently built that are frequently better—and so, in the fact that that structure can be demolished and yet still possess value as material.”
—Friedrich Nietzsche (1844–1900)
“Know how to be content and you will never be disgraced; practice self-restraint and you will never be in danger.”
—Chinese proverb.
Laozi.