SBasic language reference::If...Then...Else statement

If...Then...Else statement
Conditionally executes a group of statements, depending on the value of an expression.

Format:

  If condition Then
     [ statements ]
  [ ElseIf <elseifcondition>  Then 
     [ elseifstatements ] ]
  [ Else
     [ elsestatements ] ]
  End If

Syntax:

condition
Required. Expression. The expression you supply for condition must evaluate to 1 or 0 (True or False)
statements
Optional. One or more statements following If...Then that are executed if condition is True.
elseifcondition
Required if ElseIf is present. Same as condition.
elseifstatements
Optional. One or more statements following ElseIf...Then that are executed if the associated elseifcondition is True.
elsestatements
Optional in multiple-line form; required in single-line form that has an Else clause. One or more statements that are executed if no previous condition or elseifcondition expression is True.
End If
Required. Terminates If...Then block.

Remarks:

1. When a If...Then...Else is encountered, condition is tested. If condition is True, the statements following Then are executed. If condition is False, each ElseIf statement is evaluated in order. When a True elseifcondition is found, the statements immediately following the associated Then are executed. If no elseifcondition evaluates to True, or if there are no ElseIf statements, the statements following Else are executed. After executing the statements following Then, ElseIf, or Else, execution continues with the statement following End If.

2. The ElseIf and Else clauses are both optional. You can have as many ElseIf clauses as you want in a If...Then...Else statement, but none can appear after an Else clause.

3. If...Then...Else statements can be nested within one another as many times as needed.

See also: Select Case statement might be more useful when evaluating a single expression that has several possible values.

Example:

  Input "Imput your number: ", Number

  if Number < 10 then
    Digits = 1
  elseif Number < 100 then
    Digits = 2
  elseif Number < 1000 then
    Digits = 3
  else 
    Digits = 4
  endif

  Str = "Your number has "

  if Digits = 1 then
    str = str + Digits + " digit!"
  elseif Digits < 4 then
    str = str + Digits + " digits!"
  else
    str = str + Digits + " or more digits!"
  endif

  print Str
  input 'wait for enter to continue