Mega Code Archive
Validation
<![CDATA[
function ValidInput(InputText : TCaption) : Boolean;
{the built-in Delphi IsAlpha() function does not trap things like}
{quotation marks... -this is home-made and better}
type
TvalidInputChars = set of Char;
var
i,len : Integer;
validInputChars: TvalidInputChars;
begin
{define the SET of valid input characters}
validInputChars := ['A'..'Z', 'a'..'z'];
i := 1;
{Note: Delphi puts text from an input box into the box's .Text property when}
{focus shifts away from that box, and the TYPE of this text property is}
{TCaption}
len := Length(InputText);
{the first byte of yer actual string here contains length information...}
{so go from index 1 upwards...}
for i := 1 to len do
begin
if InputText[i] in validInputChars then
begin
Result := True
end
else
begin
Result := False;
Break;
end;
end;
end;
function TMakeOrEditBForm.checkValidSeatRange(InputText : String) : Boolean;
{at this point we've checked 'seat number' input to see if there are}
{any duff characters in the input text... sofa so good, but now we}
{need to separate out the row letters and the column numbers and make}
{sure each of these is within the required range (of seat numbers)}
{so first, find the position of the first 'number' character}
var
i, numberPos, tempInt : Integer;
tempChar : Char;
badLetter, badNumber : Boolean;
begin
badLetter := False;
badNumber := False;
for i := 1 to (Length(InputText)) do
begin
if ((InputText[i] >= '0') and (InputText[i] <= '9')) then Break;
end;
numberPos := i;
if ((numberPos < 2) or (numberPos > 2)) then Result := False;
tempChar := getRow(InputText);
tempInt := getColumn(InputText);
{at this point we have the 'row' letter in tempChar and we have the}
{'column' number in tempInt, so all that remains is to check that they}
{are both within range...}
if tempChar > last_row then
badLetter := True
else
badLetter := False;
if tempInt > last_column then
badNumber := True
else
badNumber := False;
if ((badLetter = True) or (badNumber = True)) then
begin
ShowMessage('Please input a seat number within range');
Result := False
end
else
Result := True;
end;
function TMakeOrEditBForm.checkValidSeatChars(InputText : String) : Boolean;
{the function header above includes a typecast -the InputText variable}
{is cast from type TCaption to a String type -this helps with the code below-}
{the function looks for inappropriate characters in the input text...}
var
i,numberPos : Integer;
badLetter, badNumber : Boolean;
tempChar : Char;
tempString : String;
len: Integer;
begin
badLetter := False;
badNumber := False;
{first check that all input characters are within the required}
{range (of characters) and watch out for users pressing return on}
{a blank seat no box...}
len := Length(InputText);
if len = 0 then
begin
tempChar := '#'; {this will generate an error -simplifies the logic...}
end
else
begin
tempChar := InputText[1];
end;
if ((tempChar >= 'A') and (tempChar <= 'Z')) then
badLetter := False
else
begin
badLetter := True;
end;
for i := 2 to (Length(InputText)) do
begin
if ((InputText[i] >= '0') and (InputText[i] <= '9')) then
badNumber := False
else
begin
badNumber := True;
end;
if badNumber = True then Break;
end;
{if bad letters or numbers exit function and return 'False'...}
if ((badLetter = True) or (badNumber = True)) then
begin
Result := False
end
else
Result := True;
end;
function TPerformanceDBMS.CheckValidFile(dataString: String): Boolean;
{check the data in a file specified by the user in an Open dialogue box}
{-if the data is not in an appropriate form then return False...}
{for a data file to be valid, there must be (last_row X last_column)}
{'tuples' (for name and booked?) and there must be a 'T' or an 'F' in}
{the second place of each 'triple'... also, at the start of the data}
{there should be two extra fields for date and time, so the total}
{number of fields should be ((last_row X last_column) X 2) + 2) }
var
i,j,pos: Integer;
numberOfFields: Integer;
noTorF, THere, FHere: Boolean;
thisField: String;
len,width: Integer;
row : Char;
column : Integer;
correctNumber: Integer;
numRows: Integer;
begin
numRows := 0;
THere := True;
FHere := False;
noTorF := False;
i := 1;
pos := 1;
numberOfFields := 0;
{work out the correct number of fields (see formula above) but remember}
{we must treat 'row' as an integer and not as the character that it is...}
for row := 'A' to last_row do
begin
Inc(numRows);
end;
correctNumber := (((numRows * last_column) * 2) + 2);
len := Length(dataString);
{FIRSTLY check the file to see if there are the required number of commas}
{because if there aren't there's no point going on to the next section...}
for i := 1 to len do
begin
if (dataString[i] = ',') then
begin
Inc(numberOfFields);
end;
end;
if (numberOfFields = correctNumber) then
begin
for row := 'A' to last_row do
begin
for column := 1 to last_column do
begin
pos := i;
while not (dataString[i] = ',') do
begin
Inc(i);
if i >= len then Break;
end;
{re-initialise the thisField variable on each pass}
thisField := '';
{skip a comma by incrementing i...}
Inc(i);
pos := i;
while not (dataString[i] = ',') do
begin
Inc(i);
if i >= len then Break;
end;
{make sure there are 'T's or 'F's after date and time}
if numberOfFields > 3 then
begin
thisField := Copy(dataString, pos, i-pos);
if thisField = 'T' then
THere := True;
if thisField = 'F' then
FHere := True;
if not (THere or FHere) then
NoTorF := True;
end;
{re-initialise the thisField variable...}
thisField := '';
{skip a comma by incrementing i...}
Inc(i);
end; {for}
end; {for}
end; {if}
if ((numberOfFields = correctNumber) and (noTorF = False)) then
begin
Result := True;
end
else
begin
Result := False;
end;
end;
function TForm1.CheckValidDate(dateString : String):Boolean;
{this function is NOT a DIY error-checking function- instead it takes
advantage of internal Delphi code wherein IF an invalid date is input,
Delphi generates an 'exception', and the 'try...except on' block of code
below is a way of 'trapping' Delphi's exception such that instead of
Delphi displaying an error message to the user we can display our own...
also, writing a routine to check valid dates would be a real pain...
dates will be in the dd/mm/yy format IF Windows is set up that way...}
var
date : TDateTime;
redundant : Integer;
InValid : Boolean;
len: Integer;
begin
InValid := False;
try
date := StrToDate(dateString);
except on EConvertError do
InValid := True;
end;
{if user input 1/1/98 then the code above would consider it valid -HOWEVER
for various procedures to work properly in the system we MUST have dates
in dd/mm/yy format (eg 01/01/98) so we must check that separately...}
len := Length(dateString);
if not (len = 8) then
begin
InValid := True;
end;
if InValid = True then
begin
ShowMessage('This is not a valid date -dates should be in dd/mm/yy format');
Result := False;
end
else
begin
Result := True
end;
end;
function TForm1.CheckValidTime(timeString: String): Boolean;
var
moreOrLess: Integer;
mChar, eChar: String;
firstLetter: String;
begin
firstLetter := Copy(timeString,1,1);
if firstLetter = 'M' then
begin
Result := True;
end
else if firstLetter = 'm' then
begin
Result := True;
end
else if firstLetter = 'E' then
begin
Result := True;
end
else if firstLetter = 'e' then
begin
Result := True;
end
else
begin
ShowMessage('This is not a valid time -please use Matinee or Evening');
Result := False;
end;
end;
function AlphaBetic(InputText : TCaption) : Boolean;
{the built-in IsAlpha() function does not trap things like quotation marks...}
{and the other validation functions below are hand-made for similar reasons}
var
i,len : Integer;
begin
i := 1;
{Delphi puts text from an input box into the box's .Text property when}
{focus shifts away from that box, and the TYPE of this text property is}
{TCaption}
len := Length(InputText);
for i := 1 to len do
begin
if (((InputText[i] >= 'A') and (InputText[i] <= 'Z')) or
((InputText[i] >= 'a') and (InputText[i] <= 'z')) or
(InputText[i] = ' ')) then
begin
Result := True
end
else
begin
Result := False;
Break;
end;
end;
end;
function AlphaNumeric(InputText : TCaption) : Boolean;
var
i,len : Integer;
begin
i := 1;
len := Length(InputText);
for i := 1 to len do
begin
if (((InputText[i] >= 'A') and (InputText[i] <= 'Z')) or
((InputText[i] >= 'a') and (InputText[i] <= 'z')) or
((InputText[i] >= '0') and (InputText[i] <= '9'))) then
begin
Result := True
end
else
begin
Result := False;
Break;
end;
end;
end;
function NumericInteger(InputText : TCaption) : Boolean;
var
i,len : Integer;
begin
i := 1;
len := Length(InputText);
for i := 1 to len do
begin
if ((InputText[i] >= '0') and (InputText[i] <= '9')) then
begin
Result := True
end
else
begin
Result := False;
Break;
end;
end;
end;
function NumericDecimal(InputText : TCaption) : Boolean;
var
i,len,dotcount : Integer;
begin
i := 1;
{we need to check to see if there is more than one decimal point...}
dotcount := 0;
len := Length(InputText);
for i := 1 to len do
begin
if (((InputText[i] >= '0') and (InputText[i] <= '9')) or
(InputText[i] = '.')) then
begin
if (dotcount > 1) then Result := False;
Result := True
end
else
begin
Result := False;
Break;
end;
if (InputText[i] = '.') then Inc(dotcount);
end;
end;
function ValidInput(InputText : TCaption) : Boolean;
{the built-in Delphi IsAlpha() function does not trap things like}
{quotation marks... -this is home-made and better}
var
i,len : Integer;
begin
i := 1;
{Note: Delphi puts text from an input box into the box's .Text property when}
{focus shifts away from that box, and the TYPE of this text property is}
{TCaption}
len := Length(InputText);
{the first byte of yer actual string here contains length information...}
{so go from index 1 upwards...}
for i := 1 to len do
begin
{use SET syntax -it's better coding than this...}
if (((InputText[i] >= 'A') and (InputText[i] <= 'Z')) or
((InputText[i] >= 'a') and (InputText[i] <= 'z'))) then
begin
Result := True
end
else
begin
Result := False;
Break;
end;
end;
end;
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