HP C A.06.05 Reference Manual

Preprocessing Directives
_Pragma
Chapter 7200
_Pragma
_Pragma is a preprocessing unary operator.
Syntax
_Pragma (string-literal)
_Pragma is a new preprocessing operator and is a part of C99 standards. The string literal is
destringized by deleting the L prefix, if present. _Pragma deletes the leading and trailing
double quotes, replacing each escape sequence by a double-quote, and replacing the escape
sequence by a single backlash. The resulting sequence of characters is processed to produce
preprocessor tokens that are executed as if they were preprocessed tokens in a pragma
directive.
The _Pragma operator provides portability in the use of an existing #pragma C preprocessor
construct. These pragmas are processed as defined in its implementation. Most C
implementations provide pragmas that are very similar in meaning and functionality. The
_Pragma operator can be used in the replacement text of a macro, so as to aid in abstracting
these specific pragmas a level higher.
Examples
The following examples list the usage of the _Pragma operator:
Example 7-1 _Pragma Operator Usage
A directive of the form,
#pragma listing on "..\listing.dir"
can also be expressed as,
_Pragma (listing on \"..\\listing.dir\"")
The latter form is processed as earlier, if it appears literally as shown or it results from macro
replacement, as in:
# define LISTING(x) PRAGMA(listing on #x)
# define PRAGMA(x) _Pragma(#x)
LISTING (..\listing.dir)
Example 7-2 _Pragma Operator Usage
_Pragma("ALIGN 4")