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<html lang="en"><head><title>Using the GNU Compiler Collection (GCC)</title><meta http-equiv="Content-Type" content="text/html"><meta name="description" content="Using the GNU Compiler Collection (GCC)"><meta name="generator" content="makeinfo 4.6"><!--Copyright © 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. <p>Permission is granted to copy, distribute and/or modify this documentunder the terms of the GNU Free Documentation License, Version 1.2 orany later version published by the Free Software Foundation; with theInvariant Sections being "GNU General Public License" and "FundingFree Software", the Front-Cover texts being (a) (see below), and withthe Back-Cover Texts being (b) (see below). A copy of the license isincluded in the section entitled "GNU Free Documentation License". <p>(a) The FSF's Front-Cover Text is: <p>A GNU Manual <p>(b) The FSF's Back-Cover Text is: <p>You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.--><meta http-equiv="Content-Style-Type" content="text/css"><style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller }--></style></head><body><div class="node"><p>Node: <a name="Function%20Names">Function Names</a>,Next: <a rel="next" accesskey="n" href="Return-Address.html#Return%20Address">Return Address</a>,Previous: <a rel="previous" accesskey="p" href="Incomplete-Enums.html#Incomplete%20Enums">Incomplete Enums</a>,Up: <a rel="up" accesskey="u" href="C-Extensions.html#C%20Extensions">C Extensions</a><hr><br></div><h3 class="section">Function Names as Strings</h3><p>GCC provides three magic variables which hold the name of the currentfunction, as a string. The first of these is <code>__func__</code>, whichis part of the C99 standard:<pre class="display"> The identifier <code>__func__</code> is implicitly declared by the translator as if, immediately following the opening brace of each function definition, the declaration <pre class="smallexample"> static const char __func__[] = "function-name"; </pre> appeared, where function-name is the name of the lexically-enclosing function. This name is the unadorned name of the function. </pre> <p><code>__FUNCTION__</code> is another name for <code>__func__</code>. Olderversions of GCC recognize only this name. However, it is notstandardized. For maximum portability, we recommend you use<code>__func__</code>, but provide a fallback definition with thepreprocessor:<pre class="smallexample"> #if __STDC_VERSION__ < 199901L # if __GNUC__ >= 2 # define __func__ __FUNCTION__ # else # define __func__ "<unknown>" # endif #endif </pre> <p>In C, <code>__PRETTY_FUNCTION__</code> is yet another name for<code>__func__</code>. However, in C++, <code>__PRETTY_FUNCTION__</code> containsthe type signature of the function as well as its bare name. Forexample, this program:<pre class="smallexample"> extern "C" { extern int printf (char *, ...); } class a { public: void sub (int i) { printf ("__FUNCTION__ = %s\n", __FUNCTION__); printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__); } }; int main (void) { a ax; ax.sub (0); return 0; } </pre><p>gives this output:<pre class="smallexample"> __FUNCTION__ = sub __PRETTY_FUNCTION__ = void a::sub(int) </pre> <p>These identifiers are not preprocessor macros. In GCC 3.3 andearlier, in C only, <code>__FUNCTION__</code> and <code>__PRETTY_FUNCTION__</code>were treated as string literals; they could be used to initialize<code>char</code> arrays, and they could be concatenated with other stringliterals. GCC 3.4 and later treat them as variables, like<code>__func__</code>. In C++, <code>__FUNCTION__</code> and<code>__PRETTY_FUNCTION__</code> have always been variables. </body></html>⌨️ 快捷键说明
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