When using text variables are usually declared
as Strings. A number of component properties are also string (text)
values. For example Button1.Caption or Edit1.Text.
For example sSourceText can be declared as String under var.
sSourceText := ‘The man walks’
Take note that each character in a String variable can be referred to by
using an index. The character sSourceText[2] would for instance be 'h'.
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1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
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T |
h |
e |
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m |
a |
n |
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w |
a |
l |
k |
s |
Even the spaces therefore has index values
(see characters 4 and 8 above).
Furthermore Delphi has a number of prewritten functions and procedures
that can be used to get properties of String variables or to manipulate
the variables. Therefore to:
- Determine the position of a piece of
a text within a string
IntegerVariable := Pos(StrToBeFound, SourceText);
For example: iX := Pos (‘m’, sSourceText);
{The value of iX is now: 5}
- Display a certain character within a
string using square brackets at the end of a variable.
StringVariable := SourceText[CharacterPosition];
For example: sNewText := sSourceText[2];
{The value of sNewText is now: ‘h’}
- Display a certain section of text
within a string.
For example: StringVariable := Copy(SourceText, BeginPosition,
Length);
sNewText := Copy(sSourceText, 5, 3);
{The value of sNewText is now: ‘man’}
- Insert a certain section of text
within a string.
For example: Insert(InsertText, SourceText, Position);
Insert(‘big ’, sSourceText, 5);
{The value of sSourceText is now: ‘The big man walks’}
- Remove a certain section of text
within a string.
For example: Delete(SourceText, Position, Length);
Delete(sSourceText, 5, 4);
{The value of sSourceText is now: ‘The walks’}
- Determine the length of a string.
For example: IntegerVariable := Length(SourceText);
iX := Length(sSourceText);
{The value of iX is now: 13}
- Change the whole string to lowercase.
For example: LowerCase(SourceText);
LowerCase(sSourceText);
{The value of sSourceText is now: ‘the man walks’}
- Change the whole string to uppercase.
For example: UpperCase(SourceText);
UpperCase(sSourceText);
{The value of sSourceText is now: ‘THE MAN WALKS’}
Take note: Use UpCase for Char type.
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