Delphi Language Guide Delphi for Microsoft Win32 Delphi for the Microsoft. Net framework

Case Statements
The case statement may provide a readable alternative to deeply nested if conditionals. A case statement has the
form
case selectorExpression of
   caseList1: statement1;
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---

     ...
   caseListn: statementn;
end
where selectorExpression is any expression of an ordinal type (string types are invalid) and each caseList is one of
the following:
A numeral, declared constant, or other expression that the compiler can evaluate without executing your
program. It must be of an ordinal type compatible with selectorExpression. Thus 
7
, True, 
4 + 5 * 3
, 'A', and
Integer('A')
 can all be used as caseLists, but variables and most function calls cannot. (A few built-in
functions like 
Hi
 and 
Lo
 can occur in a caseList. See Constant expressions.)
A subrange having the form First..Last, where First and Last both satisfy the criterion above and First is less
than or equal to Last.
A list having the form item1, ..., itemn, where each item satisfies one of the criteria above.
Each value represented by a caseList must be unique in the case statement; subranges and lists cannot overlap. A
case statement can have a final else clause:
case selectorExpression of
   caseList1: statement1;
      ...
   caselistn: statementn;
   else
      statements;
end
where statements is a semicolon-delimited sequence of statements. When a case statement is executed, at most
one of statement1 ... statementn is executed. Whichever caseList has a value equal to that of selectorExpression
determines the statement to be used. If none of the caseLists has the same value as selectorExpression, then the
statements in the else clause (if there is one) are executed.
The case statement
case I of
   1..5: Caption := 'Low';
   6..9: Caption := 'High';
   0, 10..99: Caption := 'Out of range';
   else
     Caption := '';
end
is equivalent to the nested conditional
if I in [1..5] then
   Caption := 'Low';
else if I in [6..10] then
        Caption := 'High';
     else if (I = 0) or (I in [10..99]) then
            Caption := 'Out of range'
          else
            Caption := '';
Other examples of case statements
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---

case MyColor of
   Red: X := 1;
   Green: X := 2;
   Blue: X = 3;
   Yellow, Orange, Black: X := 0;
end;
case Selection of
   Done: Form1.Close;
   Compute: calculateTotal(UnitCost, Quantity);
   else
      Beep;
end;
Control Loops
Loops allow you to execute a sequence of statements repeatedly, using a control condition or variable to determine
when the execution stops. Delphi has three kinds of control loop: repeat statements, while statements, and for
statements.
You can use the standard 
Break
 and 
Continue
 procedures to control the flow of a repeat, while, or for statement.
Break
 terminates the statement in which it occurs, while 
Continue
 begins executing the next iteration of the
sequence.