User manual

264
mikoC PRO for dsPIC
MikroElektronika
Conditional Compilation
Conditional compilation directives are typically used to make source programs easy to change and easy to compile
in different execution environments. The mikroC PRO for dsPIC30/33 and PIC24 supports conditional compilation by
replacing the appropriate source-code lines with a blank line.
All conditional compilation directives must be completed in the source or include le in which they have begun.
Directives #if, #elif, #else, and #endif
The conditional directives #if, #elif, #else, and #endif work very similar to the common C conditional statements.
If the expression you write after #if has a nonzero value, the line group immediately following the #if directive is
retained in the translation unit.
The syntax is:
#if constant_expression_1
<section_1>
[#elif constant_expression_2
<section_2>]
...
[#elif constant_expression_n
<section_n>]
[#else
<nal_section>]
#endif
Each #if directive in a source le must be matched by a closing #endif directive. Any number of #elif directives
can appear between #if and #endif directives, but at most one #else directive is allowed. The #else directive, if
present, must be the last directive before #endif.
sections can be any program text that has meaning to compiler or preprocessor. The preprocessor selects a single
section by evaluating constant_expression following each #if or #elif directive until it nds a true (nonzero)
constant expression. The constant expressions are subject to macro expansion.
If all occurrences of constant-expression are false, or if no #elif directives appear, the preprocessor selects the text
block after the #else clause. If the #else clause is omitted and all instances of constant_expression in the #if
block are false, no section is selected for further processing.
Any processed section can contain further conditional clauses, nested to any depth. Each nested #else, #elif, or
#endif directive belongs to the closest preceding the #if directive.
The net result of the preceding scenario is that only one code section (possibly empty) will be compiled.