expressão lógicaLógicoRequired
Condition that determines whether the corresponding block runs.
COMMANDPublished
IF ... ENDIF
IF <expressão lógica> ... [ELSEIF <expressão>] ... [ELSE ...] ENDIFExecutes a block of commands according to the result of a logical expression.
Overview
IF ... ENDIF controls instruction execution from a condition. When the expression is true (.T.), the block after IF runs. If it is false (.F.), ELSEIF clauses may test alternatives in order and ELSE may provide a default path. After one alternative runs, control continues after ENDIF.
Syntax
IF <expressão lógica> ... [ELSEIF <expressão>] ... [ELSE ...] ENDIFParameters
ELSEIFCláusulaOptional
Allows alternative conditions to be evaluated in sequence.
ELSECláusulaOptional
Optional block executed when no previous condition returns .T.
Simple decision with ELSE
User Function ExDueDate(dDueDate)
Local cMessage := ""
If Date() > dDueDate
cMessage := "Due date exceeded"
Else
cMessage := "Within the deadline"
EndIf
MsgInfo(cMessage)
ReturnExpected result
The comparison determines which block assigns the message shown to the user.
Multiple alternatives with ELSEIF
User Function ExFaixa(nTotal)
Local cFaixa := ""
If nTotal > 100000
cFaixa := "Especial"
ElseIf nTotal > 50000
cFaixa := "Alta"
ElseIf nTotal > 10000
cFaixa := "Média"
Else
cFaixa := "Padrão"
EndIf
Return cFaixaExpected result
The first true condition sets the tier; remaining alternatives are ignored.
Combining logical operators
User Function ExAcesso(lAtivo, nNivel)
Local lPermitido := .F.
If lAtivo .And. nNivel >= 3
lPermitido := .T.
EndIf
Return lPermitidoExpected result
Access is allowed only when both conditions are true.
- Make the condition explicitly produce a logical value.
- Use ELSE when a default behavior is required.
- Order ELSEIF clauses from most specific to most general.
- Prefer short conditions and extract complex validations into clearly named functions.
- Use DO CASE when many alternatives make ELSEIF sequences hard to read.
- Poorly grouped comparisons and logical operators may select an unexpected path.
- Deeply nested IF statements reduce readability and increase the chance of closing the wrong structure.
- A broad early ELSEIF condition may make later alternatives unreachable.
- Although historical documentation states that NIL is treated as .F. since Protheus 5.07, relying on it hides errors; validate the condition type.
- Every IF requires a matching ENDIF.