DIRECTIVEPublished

#ifdef

#ifdef <identificador> ... [#else ...] #endif

Includes a block in compilation only when a given identifier is defined.

Compilação condicionalPré-processadorAmbientes

01 · OVERVIEW

Overview

#ifdef checks at preprocessing time for a symbol created by #define or supplied by the environment. Accepted code reaches the compiler; rejected code is absent from the final object.

02 · SYNTAX

Syntax

#ifdef <identificador> ... [#else ...] #endif

03 · PRACTICAL EXAMPLE

Code controlled by a symbol

#define AMBIENTE_HOMOLOGACAO

User Function ExIfDef()
#ifdef AMBIENTE_HOMOLOGACAO
    MsgInfo("Compilação de homologação")
#else
    MsgInfo("Compilação padrão")
#endif
Return

Expected result

Only one branch enters the compiled object.

BEST PRACTICES

The decision happens at compilation, not runtime.
Use #else for an alternative and always close with #endif.

COMMON PITFALLS

Do not use compilation symbols for operational configuration that must change without recompilation.
Too many source variants increase testing cost.

#ifdef

Overview

Syntax

Code controlled by a symbol

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