IIf
Conditional function that returns one of two values.
IIf ( condition, expr_if_true, expr_if_false )
condition
IIf returns a different numeric or string or UDT value depending of the result of a conditional expression. Its typical use is in the middle of an expression; it avoids splitting it to put a conditional in the middle.
IIf only evaluates the expression that it needs to return. This saves time, and can also be useful to prevent evaluating expressions that might be invalid depending on the condition.
Warning: The ability to accept mixed numeric types, strings and UDTs is only supported from the fbc version 0.90.
is equivalent to:
Syntax
IIf ( condition, expr_if_true, expr_if_false )
Parameters
condition
The condition to test.
A non-zero value evaluates as true, while a value of zero evaluates as false.
expr_if_trueA non-zero value evaluates as true, while a value of zero evaluates as false.
An expression to evaluate and return if condition is true.
It must return:
It must return:
- a numeric value, which can be an integer, floating point number or a pointer,
- or a string value,
- or an UDT value.
An expression to evaluate and return if condition is false.
It must be same type as expr_if_true (either numeric, either string or UDT).
It must be same type as expr_if_true (either numeric, either string or UDT).
Description
IIf returns a different numeric or string or UDT value depending of the result of a conditional expression. Its typical use is in the middle of an expression; it avoids splitting it to put a conditional in the middle.
IIf only evaluates the expression that it needs to return. This saves time, and can also be useful to prevent evaluating expressions that might be invalid depending on the condition.
Warning: The ability to accept mixed numeric types, strings and UDTs is only supported from the fbc version 0.90.
Example
Dim As Integer a, b, x, y, z
a = (x + y + IIf(b > 0, 4, 7)) \ z
a = (x + y + IIf(b > 0, 4, 7)) \ z
is equivalent to:
Dim As Integer a, b, x, y, z, temp
If b > 0 Then temp = 4 Else temp = 7
a = (x + y + temp) \ z
If b > 0 Then temp = 4 Else temp = 7
a = (x + y + temp) \ z
Dim As Integer I
I = -10
Print I, IIf(I>0, "positive", IIf(I=0, "null", "negative"))
I = 0
Print I, IIf(I>0, "positive", IIf(I=0, "null", "negative"))
I = 10
Print I, IIf(I>0, "positive", IIf(I=0, "null", "negative"))
Sleep
I = -10
Print I, IIf(I>0, "positive", IIf(I=0, "null", "negative"))
I = 0
Print I, IIf(I>0, "positive", IIf(I=0, "null", "negative"))
I = 10
Print I, IIf(I>0, "positive", IIf(I=0, "null", "negative"))
Sleep
Type UDT1
Dim As Integer I1
End Type
Type UDT2 Extends UDT1
Dim As Integer I2
End Type
Dim As UDT1 u1, u10 = (1)
Dim As UDT2 u2, u20 = (2, 3)
u1 = IIf(0, u10, u20)
Print u1.I1
u1 = IIf(1, u10, u20)
Print u1.I1
u2 = IIf(0 , u10, u20)
Print u2.I1; u2.I2
'u2 = Iif(1, u10, u20) ''Invalid assignment/conversion
Sleep
Dim As Integer I1
End Type
Type UDT2 Extends UDT1
Dim As Integer I2
End Type
Dim As UDT1 u1, u10 = (1)
Dim As UDT2 u2, u20 = (2, 3)
u1 = IIf(0, u10, u20)
Print u1.I1
u1 = IIf(1, u10, u20)
Print u1.I1
u2 = IIf(0 , u10, u20)
Print u2.I1; u2.I2
'u2 = Iif(1, u10, u20) ''Invalid assignment/conversion
Sleep
Dialect Differences
- Not available in the -lang qb dialect unless referenced with the alias __Iif.
Differences from QB
- New to FreeBASIC
See also