macros_misc.sgml

GLIB-C的最新源代码

<!-- ##### MACRO G_GNUC_FUNCTION ##### -->
<para>
Expands to the GNU C <literal>__FUNCTION__</literal> variable if the 
compiler is <command>gcc</command>, or "" if it isn't. The GNU C 
<literal>__FUNCTION__</literal> variable contains the name of the 
current function. See the GNU C documentation for details. 
</para>



<!-- ##### MACRO G_GNUC_PRETTY_FUNCTION ##### -->
<para>
Expands to the GNU C <literal>__PRETTY_FUNCTION__</literal> variable 
if the compiler is <command>gcc</command>, or "" if it isn't.
The GNU C <literal>__PRETTY_FUNCTION__</literal> variable contains the 
name of the current function. For a C program this is the same as the 
<literal>__FUNCTION__</literal> variable but for C++ it also includes 
extra information such as the class and function prototype. See the 
GNU C documentation for details. 
</para>



<!-- ##### MACRO G_GNUC_NO_INSTRUMENT ##### -->
<para>
Expands to the GNU C <literal>no_instrument_function</literal> function 
attribute if the compiler is <command>gcc</command>. Functions with this 
attribute will not be 
instrumented for profiling, when the compiler is called with the
<option>-finstrument-functions</option> option.
See the GNU C documentation for details. 
</para>



<!-- ##### MACRO G_HAVE_GNUC_VISIBILITY ##### -->
<para>
This macro is defined as 1 if the the compiler supports ELF visibility 
attributes (currently only <command>gcc</command>).
</para>

Since: 2.6



<!-- ##### MACRO G_GNUC_INTERNAL ##### -->
<para>
Expands to the GNU C <literal>visibility(hidden)</literal> attribute if the 
compiler supports it  (currently only <command>gcc</command>). This attribute 
can be used for marking library functions as being used internally to the lib 
only, to not create inefficient PLT entries. Note that static functions do not 
need to be marked as internal in this way. See the GNU C documentation for details. 
</para>

Since: 2.6



<!-- ##### MACRO G_LIKELY ##### -->
<para>
Hints the compiler that the expression is likely to evaluate to a true
value. The compiler may use this information for optimizations.
</para>
<informalexample><programlisting>
if (G_LIKELY (random () != 1))
  g_print ("not one");
</programlisting></informalexample>

@expr: the expression
@Since: 2.2


<!-- ##### MACRO G_UNLIKELY ##### -->
<para>
Hints the compiler that the expression is unlikely to evaluate to a true
value. The compiler may use this information for optimizations.
</para>
<informalexample><programlisting>
if (G_UNLIKELY (random () == 1))
  g_print ("a random one");
</programlisting></informalexample>

@expr: the expression
@Since: 2.2


<!-- ##### MACRO G_STRLOC ##### -->
<para>
Expands to a string identifying the current code position. 
</para>



<!-- ##### MACRO G_STRFUNC ##### -->
<para>
Expands to a string identifying the current function. 
</para>

@Since: 2.4


<!-- ##### MACRO G_GINT16_MODIFIER ##### -->
<para>
The platform dependent length modifier for constructing printf() conversion
specifiers for values of type #gint16 or #guint16. It is a string literal, 
but doesn't include the percent-sign, such that you can add precision and 
length modifiers between percent-sign and conversion specifier and append a 
conversion specifier.
</para>

<para>
The following example prints "0x7b";
<informalexample>
<programlisting>
gint16 value = 123;
g_print ("%#" G_GINT16_MODIFIER "x", value);
</programlisting>
</informalexample>
</para>

@Since: 2.4


<!-- ##### MACRO G_GINT16_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #gint16. It is a string literal, but doesn't
include the percent-sign, such that you can add precision and length
modifiers between percent-sign and conversion specifier.
</para>

<para>
<informalexample>
<programlisting>
gint16 in;
gint32 out;
sscanf ("42", "%" G_GINT16_FORMAT, &amp;in)
out = in * 1000;
g_print ("%" G_GINT32_FORMAT, out);
</programlisting>
</informalexample>
</para>



<!-- ##### MACRO G_GUINT16_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #guint16. See also #G_GINT16_FORMAT.
</para>



<!-- ##### MACRO G_GINT32_MODIFIER ##### -->
<para>
The platform dependent length modifier for constructing printf() conversion
specifiers for values of type #gint32 or #guint32. See also #G_GINT16_MODIFIER.
</para>

@Since: 2.4


<!-- ##### MACRO G_GINT32_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #gint32. See also #G_GINT16_FORMAT.
</para>



<!-- ##### MACRO G_GUINT32_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #guint32. See also #G_GINT16_FORMAT.
</para>



<!-- ##### MACRO G_GINT64_MODIFIER ##### -->
<para>
The platform dependent length modifier for constructing printf() conversion
specifiers for values of type #gint64 or #guint64. See also #G_GINT16_MODIFIER.
</para>

<note>
<para>
Some platforms do not support printing 64 bit integers,
even though the types are supported. On such platforms #G_GINT64_MODIFIER
is not defined.
</para>
</note>

@Since: 2.4


<!-- ##### MACRO G_GINT64_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #gint64. See also #G_GINT16_FORMAT.
</para>

<note>
<para>
Some platforms do not support scanning and printing 64 bit integers,
even though the types are supported. On such platforms #G_GINT64_FORMAT
is not defined. Note that scanf() may not support 64 bit integers, even
if #G_GINT64_FORMAT is defined. Due to its weak error handling, scanf() is not 
recommended for parsing anyway; consider using g_strtoull() instead.
</para>
</note>



<!-- ##### MACRO G_GUINT64_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #guint64. See also #G_GINT16_FORMAT.
</para>

<note>
<para>
Some platforms do not support scanning and printing 64 bit integers,
even though the types are supported. On such platforms #G_GUINT64_FORMAT
is not defined.  Note that scanf() may not support 64 bit integers, even
if #G_GINT64_FORMAT is defined. Due to its weak error handling, scanf() is not 
recommended for parsing anyway; consider using g_strtoull() instead.
</para>
</note>



<!-- ##### MACRO G_GSIZE_MODIFIER ##### -->
<para>
The platform dependent length modifier for constructing printf() conversion
specifiers for values of type #gsize or #gssize. See also #G_GINT16_MODIFIER.
</para>

@Since: 2.6


<!-- ##### MACRO G_GSIZE_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #gsize. See also #G_GINT16_FORMAT.
</para>

@Since: 2.6


<!-- ##### MACRO G_GSSIZE_FORMAT ##### -->
<para>
This is the platform dependent conversion specifier for scanning and
printing values of type #gssize. See also #G_GINT16_FORMAT.
</para>

@Since: 2.6