| Description |
The If keyword is used to control the flow of code depending on the logical result of the given condition.
There are two forms of the If statement - one with an else clause, the other not.
If works as follows :
If the condition is true, then the first statement is executed. If false, then this statement is bypassed. If there is an else statement, it is executed instead.
In all cases, the Statement clause must be a contained in a begin/end block if it is longer than one statement in length.
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| Notes |
It is an easy mistake to make, but Delphi insists on no ';' after the then statement if an else statement follows.
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| Related commands |
| Boolean |
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Allows just True and False values |
| Else |
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Starts false section of if, case and try statements |
| End |
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Keyword that terminates statement blocks |
| Then |
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Part of an if statement - starts the true clause |
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| Example code : Illustrate the different flavours of the if statement |
begin
// Illustrate a simple if statement that executes true
If True then ShowMessage('True!');
// Illustrate the same, but with multiple actions
If 1 = 1 then
begin
ShowMessage('We now have');
ShowMessage('multiple lines');
end;
// Illustrate a simple if statement that fails
If 1 = 2 then ShowMessage('1 = 2');
// Illustrate an if then else statement
// Note the lack of a ';' after the 'then' clause
If False
then ShowMessage('True')
else ShowMessage('False');
// Nested if statements - Delphi sensibly manages associations
If true then
If false then
ShowMessage('Inner then satisfied')
else
ShowMessage('Inner else satisfied')
else
ShowMessage('Outer else satisfied')
end;
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| Show full unit code |
True!
We now have
multiple lines
False
Inner else satisfied
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