If...Then statement - MapBasic - 2023

Purpose

Decides which block of statements to execute (if any), based on the current value of one or more expressions.

Syntax

If if_condition Then 
	if_statement_list 
	[ ElseIf elseif_condition Then
	elseif_statement_list ] 
	[ ElseIf ... ] 
	[ Else 
	 else_statement_list ] 
End If

condition is a condition which will evaluate to TRUE or FALSE.

statement_list is a list of zero or more statements.

Restrictions

You cannot issue an If...Then statement through the MapBasic window.

Description

The If...Then statement allows conditional execution of different groups of statements.

In its simplest form, the If statement does not include an ElseIf clause, nor an Else clause:

If if_condition Then 
	 if_statement_list 
End If

With this arrangement, MapBasic evaluates the if_condition at run-time. If the if_condition is TRUE, MapBasic executes the if_statement_list; otherwise, MapBasic skips the if_statement_list.

An If statement may also include the optional Else clause:

If if_condition Then 
	 if_statement_list 
Else 
	 else_statement_list 
End If

With this arrangement, MapBasic will either execute the if_statement_list (if the condition is TRUE) or the else_statement_list (if the condition is FALSE).

Additionally, an If statement may include one or more ElseIf clauses, following the If clause (and preceding the optional Else clause):

If if_condition Then 
	 if_statement_list 
ElseIf elseif_condition Then
	 elseif_statement_list 
Else 
	 else_statement_list 
End If

With this arrangement, MapBasic tests a series of two or more conditions, continuing until either one of the conditions turns out to be TRUE or until the Else clause or the End If is reached. If the if_condition is TRUE, MapBasic will perform the if_statement_list, and then jump down to the statement which follows the End If. But if that condition is FALSE, MapBasic then evaluates the else_if_condition; if that condition is TRUE, MapBasic will execute the elseif_statement_list.

An If statement may include two or more ElseIf clauses, thus allowing you to test any number of possible conditions. However, if you are testing for one out of a large number of possible conditions, the Do Case...End Case statement is more elegant than an If statement with many ElseIf clauses.

Example

Dim today As Date
Dim today_mon, today_day, yearcount As Integer

today = CurDate() ' get current date
today_mon = Month(today) ' get the month value
today_day = Day(today) ' get the day value (1-31)

If today_mon = 1 And today_day = 1 Then
	Note "Happy New Year!" 
	yearcount = yearcount + 1
ElseIf today_mon = 2 And today_day = 14 Then
	Note "Happy Valentine's Day!"
ElseIf today_mon = 12 And today_day = 25 Then
	Note "Merry Christmas!"
Else 
	Note "Good day."
End If

See Also:

Do Case...End Case statement