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2003-06-17 Matthias Clasen <mc2@YAST_ASK> * gobject/gobject-docs.sgml: * glib/glib-docs.sgml: Add an autogenerated index. 2003-06-17 Matthias Clasen <maclas@gmx.de> * glib/tmpl/macros_misc.sgml: Document G_GNUC_DEPRECATED.
367 lines
11 KiB
Plaintext
367 lines
11 KiB
Plaintext
<!-- ##### SECTION Title ##### -->
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Miscellaneous Macros
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<!-- ##### SECTION Short_Description ##### -->
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specialized macros which are not used often.
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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These macros provide more specialized features which are not needed so often
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by application programmers.
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</para>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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</para>
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<!-- ##### MACRO G_INLINE_FUNC ##### -->
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<para>
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Used to declare inline functions. If inline functions are not supported on
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the particular platform, the macro evaluates to the empty string.
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</para>
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<!-- ##### MACRO G_STMT_START ##### -->
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<para>
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Used within multi-statement macros so that they can be used in places where
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only one statement is expected by the compiler.
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</para>
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<!-- ##### MACRO G_STMT_END ##### -->
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<para>
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Used within multi-statement macros so that they can be used in places where
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only one statement is expected by the compiler.
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</para>
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<!-- ##### MACRO G_BEGIN_DECLS ##### -->
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<para>
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Used (along with #G_END_DECLS) to bracket header files. If the
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compiler in use is a C++ compiler, adds <literal>extern "C"</literal>
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around the header.
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</para>
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<!-- ##### MACRO G_END_DECLS ##### -->
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<para>
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Used (along with #G_BEGIN_DECLS) to bracket header files. If the
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compiler in use is a C++ compiler, adds <literal>extern "C"</literal>
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around the header.
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</para>
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<!-- ##### MACRO G_N_ELEMENTS ##### -->
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<para>
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Determines the number of elements in an array. The array must be
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declared so the compiler knows its size at compile-time; this
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macro will not work on an array allocated on the heap, only static
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arrays or arrays on the stack.
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</para>
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@arr: the array
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<!-- ##### MACRO G_VA_COPY ##### -->
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<para>
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Portable way to copy <type>va_list</type> variables.
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</para>
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<para>
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In order to use this function, you must include <filename>string.h</filename>
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yourself, because this macro may use <function>memmove()</function> and GLib
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does not include <function>string.h</function> for you.
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</para>
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<!-- # Unused Parameters # -->
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@ap1: the <type>va_list</type> variable to place a copy of @ap2 in.
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@ap2: a <type>va_list</type>.
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<!-- ##### MACRO G_STRINGIFY ##### -->
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<para>
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Accepts a macro or a string and converts it into a string.
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</para>
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@macro_or_string: a macro or a string.
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<!-- ##### MACRO G_GNUC_EXTENSION ##### -->
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<para>
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Expands to <literal>__extension__</literal> when <command>gcc</command> is
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used as the compiler.
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This simply tells <command>gcc</command> not to warn about the following non-standard code
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when compiling with the <option>-pedantic</option> option.
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</para>
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<!-- ##### MACRO G_GNUC_CONST ##### -->
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<para>
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Expands to the GNU C <literal>const</literal> function attribute if the compiler is <command>gcc</command>.
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Declaring a function as const enables better optimization of the function.
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A const function doesn't examine any values except its parameters,
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and has no effects except its return value.
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See the GNU C documentation for details.
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</para>
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<note><para>
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A function that has pointer arguments and examines the data pointed to
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must <emphasis>not</emphasis> be declared const. Likewise, a function that
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calls a non-const function usually must not be const. It doesn't make sense
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for a const function to return void.
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</para></note>
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<!-- ##### MACRO G_GNUC_DEPRECATED ##### -->
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<para>
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Expands to the GNU C <literal>deprecated</literal> attribute if the compiler
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is <command>gcc</command>.
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It can be used to mark typedefs, variables and functions as deprecated.
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When called with the <option>-Wdeprecated</option> option, the compiler will
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generate warnings when deprecated interfaces are used.
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See the GNU C documentation for details.
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</para>
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@Since: 2.2
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<!-- ##### MACRO G_GNUC_NORETURN ##### -->
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<para>
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Expands to the GNU C <literal>noreturn</literal> function attribute if the
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compiler is <command>gcc</command>.
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It is used for declaring functions which never return.
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It enables optimization of the function, and avoids possible compiler
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warnings. See the GNU C documentation for details.
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</para>
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<!-- ##### MACRO G_GNUC_UNUSED ##### -->
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<para>
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Expands to the GNU C <literal>unused</literal> function attribute if the compiler is <command>gcc</command>.
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It is used for declaring functions which may never be used.
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It avoids possible compiler warnings. See the GNU C documentation for details.
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</para>
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<!-- ##### MACRO G_GNUC_PURE ##### -->
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<para>
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Expands to the GNU C <literal>pure</literal> function attribute if the compiler is <command>gcc</command>.
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Declaring a function as pure enables better optimization of the function.
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A pure function has no effects except its return value and the return
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value depends only on the parameters and/or global variables.
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See the GNU C documentation for details.
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</para>
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<!-- ##### MACRO G_GNUC_PRINTF ##### -->
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<para>
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Expands to the GNU C <literal>format</literal> function attribute if the compiler is <command>gcc</command>.
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This is used for declaring functions which take a variable number of
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arguments, with the same syntax as <function>printf()</function>.
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It allows the compiler to type-check the arguments passed to the function.
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See the GNU C documentation for details.
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</para>
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<informalexample><programlisting>
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gint g_snprintf (gchar *string,
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gulong n,
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gchar const *format,
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...) G_GNUC_PRINTF (3, 4);
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</programlisting></informalexample>
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@format_idx: the index of the argument corresponding to the format string.
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(The arguments are numbered from 1).
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@arg_idx: the index of the first of the format arguments.
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<!-- ##### MACRO G_GNUC_SCANF ##### -->
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<para>
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Expands to the GNU C <literal>format</literal> function attribute if the compiler is <command>gcc</command>.
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This is used for declaring functions which take a variable number of
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arguments, with the same syntax as <function>scanf()</function>.
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It allows the compiler to type-check the arguments passed to the function.
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See the GNU C documentation for details.
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</para>
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@format_idx: the index of the argument corresponding to the format string.
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(The arguments are numbered from 1).
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@arg_idx: the index of the first of the format arguments.
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<!-- ##### MACRO G_GNUC_FORMAT ##### -->
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<para>
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Expands to the GNU C <literal>format_arg</literal> function attribute if the compiler is <command>gcc</command>.
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This function attribute specifies that a function takes a format
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string for a <function>printf()</function>, <function>scanf()</function>,
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<function>strftime()</function> or <function>strfmon()</function> style
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function and modifies it, so that the result can be passed to a
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<function>printf()</function>, <function>scanf()</function>,
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<function>strftime()</function> or <function>strfmon()</function> style
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function (with the remaining arguments to the format function the same as
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they would have been for the unmodified string).
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See the GNU C documentation for details.
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</para>
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<informalexample><programlisting>
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gchar *g_dgettext (gchar *domain_name, gchar *msgid) G_GNUC_FORMAT (2);
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</programlisting></informalexample>
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@arg_idx: the index of the argument.
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<!-- ##### MACRO G_GNUC_FUNCTION ##### -->
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<para>
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Expands to the GNU C <literal>__FUNCTION__</literal> variable if the
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compiler is <command>gcc</command>, or "" if it isn't. The GNU C
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<literal>__FUNCTION__</literal> variable contains the name of the
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current function. See the GNU C documentation for details.
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</para>
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<!-- ##### MACRO G_GNUC_PRETTY_FUNCTION ##### -->
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<para>
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Expands to the GNU C <literal>__PRETTY_FUNCTION__</literal> variable
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if the compiler is <command>gcc</command>, or "" if it isn't.
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The GNU C <literal>__PRETTY_FUNCTION__</literal> variable contains the
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name of the current function. For a C program this is the same as the
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<literal>__FUNCTION__</literal> variable but for C++ it also includes
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extra information such as the class and function prototype. See the
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GNU C documentation for details.
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</para>
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<!-- ##### MACRO G_GNUC_NO_INSTRUMENT ##### -->
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<para>
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Expands to the GNU C <literal>no_instrument_function</literal> function
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attribute if the compiler is <command>gcc</command>. Functions with this
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attribute will not be
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instrumented for profiling, when the compiler is called with the
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<option>-finstrument-functions</option> option.
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See the GNU C documentation for details.
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</para>
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<!-- ##### MACRO G_LIKELY ##### -->
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<para>
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Hints the compiler that the expression is likely to evaluate to a true
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value. The compiler may use this information for optimizations.
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</para>
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<informalexample><programlisting>
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if (G_LIKELY (random () != 1))
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g_print ("not one");
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</programlisting></informalexample>
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@expr: the expression
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@Since: 2.2
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<!-- ##### MACRO G_UNLIKELY ##### -->
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<para>
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Hints the compiler that the expression is unlikely to evaluate to a true
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value. The compiler may use this information for optimizations.
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</para>
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<informalexample><programlisting>
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if (G_UNLIKELY (random () == 1))
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g_print ("a random one");
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</programlisting></informalexample>
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@expr: the expression
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@Since: 2.2
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<!-- ##### MACRO G_STRLOC ##### -->
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<para>
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Expands to a string identifying the current code position.
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</para>
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<!-- ##### MACRO G_GINT16_FORMAT ##### -->
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<para>
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This is the platform dependent conversion specifier for scanning and
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printing values of type #gint16. It is a string literal, but doesn't
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include the percent-sign, such that you can add precision and length
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modifiers between percent-sign and conversion specifier.
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</para>
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<para>
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<informalexample>
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<programlisting>
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gint16 in;
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gint32 out;
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sscanf ("42", "%" G_GINT16_FORMAT, &in)
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out = in * 1000;
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g_print ("%" G_GINT32_FORMAT, out);
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</programlisting>
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</informalexample>
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</para>
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<!-- ##### MACRO G_GUINT16_FORMAT ##### -->
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<para>
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This is the platform dependent conversion specifier for scanning and
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printing values of type #guint16. See also #G_GINT16_FORMAT.
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</para>
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<!-- ##### MACRO G_GINT32_FORMAT ##### -->
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<para>
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This is the platform dependent conversion specifier for scanning and
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printing values of type #gint32. See also #G_GINT16_FORMAT.
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</para>
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<!-- ##### MACRO G_GUINT32_FORMAT ##### -->
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<para>
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This is the platform dependent conversion specifier for scanning and
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printing values of type #guint32. See also #G_GINT16_FORMAT.
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</para>
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<!-- ##### MACRO G_GINT64_FORMAT ##### -->
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<para>
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This is the platform dependent conversion specifier for scanning and
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printing values of type #gint64. See also #G_GINT16_FORMAT.
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</para>
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<note>
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<para>
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Some platforms do not support scanning and printing 64 bit integers,
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even though the types are supported. On such platforms #G_GINT64_FORMAT
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is not defined.
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</para>
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</note>
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<!-- ##### MACRO G_GUINT64_FORMAT ##### -->
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<para>
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This is the platform dependent conversion specifier for scanning and
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printing values of type #guint64. See also #G_GINT16_FORMAT.
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</para>
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<note>
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<para>
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Some platforms do not support scanning and printing 64 bit integers,
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even though the types are supported. On such platforms #G_GUINT64_FORMAT
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is not defined.
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</para>
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</note>
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