1<HTML> 2<HEAD> 3<!-- This HTML file has been created by texi2html 1.52b 4 from autosprintf.texi on 22 August 2006 --> 5 6<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=UTF-8"> 7<TITLE>GNU autosprintf</TITLE> 8</HEAD> 9<BODY> 10<H1>GNU autosprintf, version 1.0</H1> 11<H2>Formatted Output to Strings in C++</H2> 12<ADDRESS>Bruno Haible</ADDRESS> 13<P> 14<P><HR><P> 15<H1>Table of Contents</H1> 16<UL> 17<LI><A NAME="TOC1" HREF="autosprintf.html#SEC1">1 Introduction</A> 18<LI><A NAME="TOC2" HREF="autosprintf.html#SEC2">2 The <CODE>autosprintf</CODE> class</A> 19<LI><A NAME="TOC3" HREF="autosprintf.html#SEC3">3 Using <CODE>autosprintf</CODE> in own programs</A> 20</UL> 21<P><HR><P> 22 23 24<H1><A NAME="SEC1" HREF="autosprintf.html#TOC1">1 Introduction</A></H1> 25 26<P> 27This package makes the C formatted output routines (<CODE>fprintf</CODE> et al.) 28usable in C++ programs, for use with the <CODE><string></CODE> strings and the 29<CODE><iostream></CODE> streams. 30 31</P> 32<P> 33It allows to write code like 34 35</P> 36 37<PRE> 38cerr << autosprintf ("syntax error in %s:%d: %s", filename, line, errstring); 39</PRE> 40 41<P> 42instead of 43 44</P> 45 46<PRE> 47cerr << "syntax error in " << filename << ":" << line << ": " << errstring; 48</PRE> 49 50<P> 51The benefits of the autosprintf syntax are: 52 53</P> 54 55<UL> 56<LI> 57 58It reuses the standard POSIX printf facility. Easy migration from C to C++. 59 60<LI> 61 62English sentences are kept together. 63 64<LI> 65 66It makes internationalization possible. Internationalization requires format 67strings, because in some cases the translator needs to change the order of a 68sentence, and more generally it is easier for the translator to work with a 69single string for a sentence than with multiple string pieces. 70 71<LI> 72 73It reduces the risk of programming errors due to forgotten state in the 74output stream (e.g. <CODE>cout << hex;</CODE> not followed by <CODE>cout << dec;</CODE>). 75</UL> 76 77 78 79<H1><A NAME="SEC2" HREF="autosprintf.html#TOC2">2 The <CODE>autosprintf</CODE> class</A></H1> 80 81<P> 82An instance of class <CODE>autosprintf</CODE> just contains a string with the 83formatted output result. Such an instance is usually allocated as an 84automatic storage variable, i.e. on the stack, not with <CODE>new</CODE> on the 85heap. 86 87</P> 88<P> 89The constructor <CODE>autosprintf (const char *format, ...)</CODE> takes a format 90string and additional arguments, like the C function <CODE>printf</CODE>. 91 92</P> 93<P> 94Conversions to <CODE>char *</CODE> and <CODE>std::string</CODE> are defined that return 95the encapsulated string. 96 97</P> 98<P> 99The destructor <CODE>~autosprintf ()</CODE> destroys the encapsulated string. 100 101</P> 102<P> 103An <CODE>operator <<</CODE> is provided that outputs the encapsulated string to the 104given <CODE>ostream</CODE>. 105 106</P> 107 108 109<H1><A NAME="SEC3" HREF="autosprintf.html#TOC3">3 Using <CODE>autosprintf</CODE> in own programs</A></H1> 110 111<P> 112To use the <CODE>autosprintf</CODE> class in your programs, you need to add 113 114</P> 115 116<PRE> 117#include "autosprintf.h" 118using gnu::autosprintf; 119</PRE> 120 121<P> 122to your source code. 123The include file defines the class <CODE>autosprintf</CODE>, in a namespace called 124<CODE>gnu</CODE>. The <SAMP>‘using’</SAMP> statement makes it possible to use the class 125without the (otherwise natural) <CODE>gnu::</CODE> prefix. 126 127</P> 128<P> 129When linking your program, you need to link with <CODE>libasprintf</CODE>, because 130that's where the class is defined. In projects using GNU <CODE>autoconf</CODE>, 131this means adding <SAMP>‘AC_LIB_LINKFLAGS([asprintf])’</SAMP> to <CODE>configure.in</CODE> 132or <CODE>configure.ac</CODE>, and using the @LIBASPRINTF@ Makefile variable that 133it provides. 134 135</P> 136<P><HR><P> 137This document was generated on 22 August 2006 using the 138<A HREF="http://wwwinfo.cern.ch/dis/texi2html/">texi2html</A> 139translator version 1.52b.</P> 140</BODY> 141</HTML> 142