| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- Copyright (C) 1987-2015 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation. A copy of |
| the license is included in the |
| section entitled "GNU Free Documentation License". |
| |
| This manual contains no Invariant Sections. The Front-Cover Texts are |
| (a) (see below), and the Back-Cover Texts are (b) (see below). |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| 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. --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>The C Preprocessor: Implementation limits</title> |
| |
| <meta name="description" content="The C Preprocessor: Implementation limits"> |
| <meta name="keywords" content="The C Preprocessor: Implementation limits"> |
| <meta name="resource-type" content="document"> |
| <meta name="distribution" content="global"> |
| <meta name="Generator" content="makeinfo"> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> |
| <link href="index.html#Top" rel="start" title="Top"> |
| <link href="Index-of-Directives.html#Index-of-Directives" rel="index" title="Index of Directives"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="Implementation-Details.html#Implementation-Details" rel="up" title="Implementation Details"> |
| <link href="Obsolete-Features.html#Obsolete-Features" rel="next" title="Obsolete Features"> |
| <link href="Implementation_002ddefined-behavior.html#Implementation_002ddefined-behavior" rel="prev" title="Implementation-defined behavior"> |
| <style type="text/css"> |
| <!-- |
| a.summary-letter {text-decoration: none} |
| blockquote.smallquotation {font-size: smaller} |
| div.display {margin-left: 3.2em} |
| div.example {margin-left: 3.2em} |
| div.indentedblock {margin-left: 3.2em} |
| div.lisp {margin-left: 3.2em} |
| div.smalldisplay {margin-left: 3.2em} |
| div.smallexample {margin-left: 3.2em} |
| div.smallindentedblock {margin-left: 3.2em; font-size: smaller} |
| div.smalllisp {margin-left: 3.2em} |
| kbd {font-style:oblique} |
| pre.display {font-family: inherit} |
| pre.format {font-family: inherit} |
| pre.menu-comment {font-family: serif} |
| pre.menu-preformatted {font-family: serif} |
| pre.smalldisplay {font-family: inherit; font-size: smaller} |
| pre.smallexample {font-size: smaller} |
| pre.smallformat {font-family: inherit; font-size: smaller} |
| pre.smalllisp {font-size: smaller} |
| span.nocodebreak {white-space:nowrap} |
| span.nolinebreak {white-space:nowrap} |
| span.roman {font-family:serif; font-weight:normal} |
| span.sansserif {font-family:sans-serif; font-weight:normal} |
| ul.no-bullet {list-style: none} |
| --> |
| </style> |
| |
| |
| </head> |
| |
| <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> |
| <a name="Implementation-limits"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Obsolete-Features.html#Obsolete-Features" accesskey="n" rel="next">Obsolete Features</a>, Previous: <a href="Implementation_002ddefined-behavior.html#Implementation_002ddefined-behavior" accesskey="p" rel="prev">Implementation-defined behavior</a>, Up: <a href="Implementation-Details.html#Implementation-Details" accesskey="u" rel="up">Implementation Details</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <hr> |
| <a name="Implementation-limits-1"></a> |
| <h3 class="section">11.2 Implementation limits</h3> |
| <a name="index-implementation-limits"></a> |
| |
| <p>CPP has a small number of internal limits. This section lists the |
| limits which the C standard requires to be no lower than some minimum, |
| and all the others known. It is intended that there should be as few limits |
| as possible. If you encounter an undocumented or inconvenient limit, |
| please report that as a bug. See <a href="http://gcc.gnu.org/onlinedocs/gcc/Bugs.html#Bugs">Reporting Bugs</a> in <cite>Using |
| the GNU Compiler Collection (GCC)</cite>. |
| </p> |
| <p>Where we say something is limited <em>only by available memory</em>, that |
| means that internal data structures impose no intrinsic limit, and space |
| is allocated with <code>malloc</code> or equivalent. The actual limit will |
| therefore depend on many things, such as the size of other things |
| allocated by the compiler at the same time, the amount of memory |
| consumed by other processes on the same computer, etc. |
| </p> |
| <ul> |
| <li> Nesting levels of ‘<samp>#include</samp>’ files. |
| |
| <p>We impose an arbitrary limit of 200 levels, to avoid runaway recursion. |
| The standard requires at least 15 levels. |
| </p> |
| </li><li> Nesting levels of conditional inclusion. |
| |
| <p>The C standard mandates this be at least 63. CPP is limited only by |
| available memory. |
| </p> |
| </li><li> Levels of parenthesized expressions within a full expression. |
| |
| <p>The C standard requires this to be at least 63. In preprocessor |
| conditional expressions, it is limited only by available memory. |
| </p> |
| </li><li> Significant initial characters in an identifier or macro name. |
| |
| <p>The preprocessor treats all characters as significant. The C standard |
| requires only that the first 63 be significant. |
| </p> |
| </li><li> Number of macros simultaneously defined in a single translation unit. |
| |
| <p>The standard requires at least 4095 be possible. CPP is limited only |
| by available memory. |
| </p> |
| </li><li> Number of parameters in a macro definition and arguments in a macro call. |
| |
| <p>We allow <code>USHRT_MAX</code>, which is no smaller than 65,535. The minimum |
| required by the standard is 127. |
| </p> |
| </li><li> Number of characters on a logical source line. |
| |
| <p>The C standard requires a minimum of 4096 be permitted. CPP places |
| no limits on this, but you may get incorrect column numbers reported in |
| diagnostics for lines longer than 65,535 characters. |
| </p> |
| </li><li> Maximum size of a source file. |
| |
| <p>The standard does not specify any lower limit on the maximum size of a |
| source file. GNU cpp maps files into memory, so it is limited by the |
| available address space. This is generally at least two gigabytes. |
| Depending on the operating system, the size of physical memory may or |
| may not be a limitation. |
| </p> |
| </li></ul> |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="Obsolete-Features.html#Obsolete-Features" accesskey="n" rel="next">Obsolete Features</a>, Previous: <a href="Implementation_002ddefined-behavior.html#Implementation_002ddefined-behavior" accesskey="p" rel="prev">Implementation-defined behavior</a>, Up: <a href="Implementation-Details.html#Implementation-Details" accesskey="u" rel="up">Implementation Details</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p> |
| </div> |
| |
| |
| |
| </body> |
| </html> |
