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#if, #elif, #else, #endif
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─────C/C++ Language─────────────────────────────────────────────────────────
Directive: #if, #elif, #else, #endif
Syntax: #if test expression
[text-block]
[#elif test expression
text-block]
∙ ∙ ∙
[#else
text-block]
#endif
Summary: Evaluates each test expression associated with an #if or
#elif directive until a true (nonzero) expression is
found, then processes the <text-block> associated with
that test expression. If there is an #else clause, the
<text-block> associated with it is processed only if no
test expression in the #if or #elif clauses has a nonzero
value.
The <test expression> can be any expression that evaluates
to a constant, and can contain logical operators and the
defined operator. It cannot use the sizeof operator, type
casts, or the float or enum types. The <text-block> can
contain C code or compiler directives.
See also: #ifdef, defined, #define, #undef
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