Case
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The reserved word Case begins a case statement. The case statement compares the value of either an enumerated type, an ordinal expression or a string, to each selector. The selector can be a constant, a subrange, or a list separated by commas. The selector field is separated from its related action(s) by a Colon.
The case statement also includes the reserved words Of and End. Else can be used if needed, when there is the possibility of no matches.
Examples
case place of
1: ShowMessage('Gold medal');
2: ShowMessage('Silver medal');
3: ShowMessage('Bronze medal');
else ShowMessage('Better luck next time');
end;
function WhatIsChar( c:char ):string;
var
s : string;
begin
s := '';
case c of
'0' .. '9' : s := 'digit (0-9)';
'a' .. 'z' : s := 'lowercase letter (a-z)';
'A' .. 'Z' : s := 'uppercase letter (A-Z)';
'+' , '-' : s := 'sign (+ or -)';
end;
result := s;
end;
Case string
The Free Pascal language allows you to "Case of" on a string variable.
const
ISO_3166_1_ALPHA_3_ANDORRA = 'AND';
ISO_3166_1_ALPHA_3_AUSTRALIA = 'AUS';
ISO_3166_1_ALPHA_3_AUSTRIA = 'AUT';
ISO_3166_1_ALPHA_3_BELGIUM = 'BEL';
ISO_3166_1_ALPHA_3_BRAZIL = 'BRA';
ISO_3166_1_ALPHA_3_CANADA = 'CAN';
ISO_3166_1_ALPHA_3_CHINA = 'CHN';
ISO_3166_1_ALPHA_3_CZECH_REPUBLIC = 'CZE';
ISO_3166_1_ALPHA_3_CYPRUS = 'CYP';
ISO_3166_1_ALPHA_3_GERMANY = 'DEU';
ISO_3166_1_ALPHA_3_DENMARK = 'DNK';
ISO_3166_1_ALPHA_3_SPAIN = 'ESP';
ISO_3166_1_ALPHA_3_ESTONIA = 'EST';
ISO_3166_1_ALPHA_3_FINLAND = 'FIN';
ISO_3166_1_ALPHA_3_FRANCE = 'FRA';
ISO_3166_1_ALPHA_3_GREECE = 'GRC';
ISO_3166_1_ALPHA_3_INDIA = 'IND';
ISO_3166_1_ALPHA_3_IRELAND = 'IRL';
ISO_3166_1_ALPHA_3_ITALY = 'ITA';
ISO_3166_1_ALPHA_3_JAPAN = 'JPN';
ISO_3166_1_ALPHA_3_LITHUANIA = 'LTU';
ISO_3166_1_ALPHA_3_LATVIA = 'LVA';
ISO_3166_1_ALPHA_3_LUXEMBOURG = 'LUX';
ISO_3166_1_ALPHA_3_MALTA = 'MLT';
ISO_3166_1_ALPHA_3_MEXICO = 'MEX';
ISO_3166_1_ALPHA_3_MONACO = 'MCO';
ISO_3166_1_ALPHA_3_MONTENEGRO = 'MNE';
ISO_3166_1_ALPHA_3_NAURU = 'NRU';
ISO_3166_1_ALPHA_3_NETHERLANDS = 'NLD';
ISO_3166_1_ALPHA_3_NORWAY = 'NOR';
ISO_3166_1_ALPHA_3_POLAND = 'POL';
ISO_3166_1_ALPHA_3_PORTUGAL = 'PRT';
ISO_3166_1_ALPHA_3_REPUBLIC_OF_KOREA = 'KOR';
ISO_3166_1_ALPHA_3_RUSSIAN_FEDERATION = 'RUS';
ISO_3166_1_ALPHA_3_SAN_MARINO = 'SMR';
ISO_3166_1_ALPHA_3_SLOVAKIA = 'SVK';
ISO_3166_1_ALPHA_3_SLOVENIA = 'SVN';
ISO_3166_1_ALPHA_3_SWEDEN = 'SWE' ;
ISO_3166_1_ALPHA_3_SWITZERLAND = 'CHE';
ISO_3166_1_ALPHA_3_UNITED_KINGDOM_OF_GREAT_BRITAIN_AND_NORTHERN_IRELAND = 'GBR';
ISO_3166_1_ALPHA_3_UNITED_STATES_OF_AMERICA = 'USA';
ISO_4217_EURO = 'EUR';
ISO_4217_AUSTRALIAN_DOLLAR = 'AUD';
ISO_4217_BRAZILIAN_REAL = 'BRL';
ISO_4217_CANADIAN_DOLLAR = 'CAD';
ISO_4217_CHINESE_YUAN = 'CNY';
ISO_4217_CZECH_KORUNA = 'CZK' ;
ISO_4217_DANISH_KRONE = 'DKK' ;
ISO_4217_INDIAN_RUPEE = 'INR';
ISO_4217_POUND_STERLING = 'GBP' ;
ISO_4217_JAPANESE_YEN = 'JPY';
ISO_4217_MEXICAN_PESO = 'MXN';
ISO_4217_NORWEGIAN_KRONE = 'NOK' ;
ISO_4217_POLISH_ZLOTY = 'PLN' ;
ISO_4217_RUSSIAN_RUBLE = 'RUB' ;
ISO_4217_SOUTH_KOREAN_WON = 'KRW';
ISO_4217_SWEDISH_KRONA = 'SEK' ;
ISO_4217_SWISS_FRANC = 'CHF' ;
ISO_4217_UNITED_STATES_DOLLAR = 'USD' ;
function ISO_4217_currency_name ( ISO_3166_1_alpha_3_code: string): string;
begin
Case ISO_3166_1_alpha_3_code of
// Eurozone
ISO_3166_1_ALPHA_3_ANDORRA, ISO_3166_1_ALPHA_3_AUSTRIA,
ISO_3166_1_ALPHA_3_BELGIUM,ISO_3166_1_ALPHA_3_CYPRUS,
ISO_3166_1_ALPHA_3_GERMANY, ISO_3166_1_ALPHA_3_SPAIN,
ISO_3166_1_ALPHA_3_ESTONIA, ISO_3166_1_ALPHA_3_FINLAND,
ISO_3166_1_ALPHA_3_FRANCE, ISO_3166_1_ALPHA_3_GREECE,
ISO_3166_1_ALPHA_3_IRELAND, ISO_3166_1_ALPHA_3_ITALY,
ISO_3166_1_ALPHA_3_LITHUANIA, ISO_3166_1_ALPHA_3_LATVIA,
ISO_3166_1_ALPHA_3_LUXEMBOURG, ISO_3166_1_ALPHA_3_MONACO,
ISO_3166_1_ALPHA_3_MALTA, ISO_3166_1_ALPHA_3_MONTENEGRO,
ISO_3166_1_ALPHA_3_NETHERLANDS, ISO_3166_1_ALPHA_3_PORTUGAL,
ISO_3166_1_ALPHA_3_SAN_MARINO, ISO_3166_1_ALPHA_3_SLOVAKIA,
ISO_3166_1_ALPHA_3_SLOVENIA : result := ISO_4217_EURO ;
ISO_3166_1_ALPHA_3_AUSTRALIA, ISO_3166_1_ALPHA_3_NAURU :
result := ISO_4217_AUSTRALIAN_DOLLAR;
ISO_3166_1_ALPHA_3_BRAZIL : result := ISO_4217_BRAZILIAN_REAL;
ISO_3166_1_ALPHA_3_CANADA : result := ISO_4217_CANADIAN_DOLLAR;
ISO_3166_1_ALPHA_3_CHINA : result := ISO_4217_CHINESE_YUAN;
ISO_3166_1_ALPHA_3_CZECH_REPUBLIC : result := ISO_4217_CZECH_KORUNA ;
ISO_3166_1_ALPHA_3_DENMARK : result := ISO_4217_DANISH_KRONE ;
ISO_3166_1_ALPHA_3_INDIA : result := ISO_4217_INDIAN_RUPEE;
ISO_3166_1_ALPHA_3_JAPAN : result := ISO_4217_JAPANESE_YEN;
ISO_3166_1_ALPHA_3_MEXICO : result := ISO_4217_MEXICAN_PESO;
ISO_3166_1_ALPHA_3_NORWAY : result := ISO_4217_NORWEGIAN_KRONE ;
ISO_3166_1_ALPHA_3_POLAND : result := ISO_4217_POLISH_ZLOTY ;
ISO_3166_1_ALPHA_3_REPUBLIC_OF_KOREA : result := ISO_4217_SOUTH_KOREAN_WON ;
ISO_3166_1_ALPHA_3_RUSSIAN_FEDERATION : result := ISO_4217_RUSSIAN_RUBLE ;
ISO_3166_1_ALPHA_3_SWEDEN : result := ISO_4217_SWEDISH_KRONA ;
ISO_3166_1_ALPHA_3_SWITZERLAND : result := ISO_4217_SWISS_FRANC ;
ISO_3166_1_ALPHA_3_UNITED_KINGDOM_OF_GREAT_BRITAIN_AND_NORTHERN_IRELAND :
result := ISO_4217_POUND_STERLING ;
ISO_3166_1_ALPHA_3_UNITED_STATES_OF_AMERICA :
result := ISO_4217_UNITED_STATES_DOLLAR ;
end;
end;
Case Enumerator
If you want to use enumerators, this example is very clear:
type
TMedal = (mGold, mSilver, mBronze); // in case you want Gold to Start from 1, put this (Gold=1, ...but
const
MedalNames: array [TMedal] of string[6] = ('Gold', 'Silver', 'Bronze'); // in [TMedal], you have to change it to [Gold..Bronze] ;) suggestions to edgarrod71@gmail.com
{[ ... ]}
var
place: integer; /// place starts from 0;
M: TMedal;
{[ ... ]}
M := TMedal(place);
case M of
mGold: ShowMessage(Medalnames[M] + ' medal');
mSilver: ShowMessage(Medalnames[M] + ' medal');
mBronze: ShowMessage(Medalnames[M] + ' medal');
else
ShowMessage('Better luck next time! :)');
end;
Another example without MedalNames array...
type
TMedal = (Gold, Silver, Bronze); // avoid the "m"
{[ ... ]}
var
place: integer; /// place starts from 0;
M: TMedal;
S: string;
{[ ... ]}
M := TMedal(place);
case M of
Gold: writeStr(S, M);
Silver: writeStr(S, M);
Bronze: writeStr(S, M);
else
S := 'Better luck next time! ;)';
end;
ShowMessage(S);
Hexadecimal input
If hexadecimal number are used, it is considered that they are unsigned:
case place of
$1: ShowMessage('Gold medal');
$2: ShowMessage('Silver medal');
$3: ShowMessage('Bronze medal');
else ShowMessage('Better luck next time');
end;
If a hexadecimal is a different kind of a variable, for example Shortint, values shall be cast:
case place of
Shortint($C3): ShowMessage('Gold medal'); //C3= -61;
Shortint($34): ShowMessage('Silver medal');
Shortint($58): ShowMessage('Bronze medal');
else ShowMessage('Better luck next time');
end;
or another solution can be used:
var
myplace : ShortInt;
place : Byte absolute myplace;
begin
myplace:=-61;
case place of
$C3: ShowMessage('Gold medal');
$34: ShowMessage('Silver medal');
$58: ShowMessage('Bronze medal');
else ShowMessage('Better luck next time');
end;
Variant Record
Case is used in Variant Record, too. A Variant Record is also called a tagged union.
type
ScaleKelvin = 223 .. 323;
ScaleCelsius = -50 .. 50;
TemperatureScale = ( celsius, kelvin ) ;
Temperature = record
case scale : TemperatureScale of
celsius : (celsius_value : ScaleCelsius);
kelvin : (kelvin_value : ScaleKelvin);
end;