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<!-- This HTML file has been created by texi2html 1.52a
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from autosprintf.texi on 12 June 2003 -->
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<TITLE>GNU autosprintf</TITLE> |
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<H1>GNU autosprintf, version 1.0</H1> |
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<H2>Formatted Output to Strings in C++</H2> |
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<ADDRESS>Bruno Haible</ADDRESS> |
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<P>
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<P><HR><P> |
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<H1>Table of Contents</H1> |
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<UL>
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<LI><A NAME="TOC1" HREF="autosprintf.html#SEC1">1 Introduction</A> |
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<LI><A NAME="TOC2" HREF="autosprintf.html#SEC2">2 The <CODE>autosprintf</CODE> class</A> |
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<LI><A NAME="TOC3" HREF="autosprintf.html#SEC3">3 Using <CODE>autosprintf</CODE> in own programs</A> |
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</UL>
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<P><HR><P> |
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<H1><A NAME="SEC1" HREF="autosprintf.html#TOC1">1 Introduction</A></H1> |
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<P>
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This package makes the C formatted output routines (<CODE>fprintf</CODE> et al.) |
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usable in C++ programs, for use with the <CODE><string></CODE> strings and the |
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<CODE><iostream></CODE> streams. |
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</P>
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<P>
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It allows to write code like |
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</P>
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<PRE>
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cerr << autosprintf ("syntax error in %s:%d: %s", filename, line, errstring); |
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</PRE>
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instead of |
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</P>
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cerr << "syntax error in " << filename << ":" << line << ": " << errstring; |
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</PRE>
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<P>
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The benefits of the autosprintf syntax are: |
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</P>
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<UL>
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<LI>
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It reuses the standard POSIX printf facility. Easy migration from C to C++. |
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English sentences are kept together. |
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<LI>
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It makes internationalization possible. Internationalization requires format |
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strings, because in some cases the translator needs to change the order of a |
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sentence, and more generally it is easier for the translator to work with a |
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single string for a sentence than with multiple string pieces. |
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<LI>
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It reduces the risk of programming errors due to forgotten state in the |
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output stream (e.g. <CODE>cout << hex;</CODE> not followed by <CODE>cout << dec;</CODE>). |
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</UL>
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<H1><A NAME="SEC2" HREF="autosprintf.html#TOC2">2 The <CODE>autosprintf</CODE> class</A></H1> |
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<P>
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An instance of class <CODE>autosprintf</CODE> just contains a string with the |
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formatted output result. Such an instance is usually allocated as an |
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automatic storage variable, i.e. on the stack, not with <CODE>new</CODE> on the |
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heap. |
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</P>
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<P>
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The constructor <CODE>autosprintf (const char *format, ...)</CODE> takes a format |
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string and additional arguments, like the C function <CODE>printf</CODE>. |
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<P>
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Conversions to <CODE>char *</CODE> and <CODE>std::string</CODE> are defined that return |
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the encapsulated string. |
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</P>
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<P>
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The destructor <CODE>~autosprintf ()</CODE> destroys the encapsulated string. |
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An <CODE>operator <<</CODE> is provided that outputs the encapsulated string to the |
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given <CODE>ostream</CODE>. |
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</P>
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<H1><A NAME="SEC3" HREF="autosprintf.html#TOC3">3 Using <CODE>autosprintf</CODE> in own programs</A></H1> |
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<P>
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To use the <CODE>autosprintf</CODE> class in your programs, you need to add |
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</P>
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<PRE>
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#include "autosprintf.h" |
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using gnu::autosprintf; |
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</PRE>
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<P>
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to your source code. |
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The include file defines the class <CODE>autosprintf</CODE>, in a namespace called |
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<CODE>gnu</CODE>. The <SAMP>`using´</SAMP> statement makes it possible to use the class |
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without the (otherwise natural) <CODE>gnu::</CODE> prefix. |
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</P>
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<P>
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When linking your program, you need to link with <CODE>libasprintf</CODE>, because |
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that's where the class is defined. In projects using GNU <CODE>autoconf</CODE>, |
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this means adding <SAMP>`AC_LIB_LINKFLAGS([asprintf])´</SAMP> to <CODE>configure.in</CODE> |
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or <CODE>configure.ac</CODE>, and using the @LIBASPRINTF@ Makefile variable that |
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it provides. |
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</P>
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<P><HR><P> |
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This document was generated on 12 June 2003 using the |
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<A HREF="http://wwwinfo.cern.ch/dis/texi2html/">texi2html</A> |
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translator version 1.52a.</P>
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