
Section 9. Program Control Instructions
If ... Then ... Else Statement
Allows conditional execution, based on the evaluation of an expression.
There are two forms of the If .. Then construct: The Single Line form and the
Block form.
The single-line form is often useful for short, simple conditional tests.
The block form provides more structure and flexibility than the single-line
form and is usually easier to read, maintain, and debug.
Syntax 1 (Single Line Form)
If condition Then thenpart [Else elsepart]
Syntax 1 Description
Syntax 1 has these parts:
Part
Description
If Begins the simple If...Then control structure.
condition An expression that evaluates true (nonzero) or false (0 and
Null).
Then Identifies actions to be taken if condition is satisfied.
thenpart Statements or branches performed when condition is true.
Else Identifies actions taken if condition is not satisfied. If the
Else clause is not present, control passes to the next
statement in the program.
elsepart Statements or branches performed when condition is false.
You can have multiple statements with a condition, but they
must be on the same line and separated by colons, as in the
following statement:
TIP
If A > 10 Then A = A + 1 : B = B + A : C = C + B
Syntax 2 Block form
If condition1 Then
[statementblock-1]
[
ElseIf condition2 Then
[statementblock-2] ]
[
Else
[statementblock-n] ]
End If
9-10
Komentáře k této Příručce