GNU autosprintf, version 1.0
Formatted Output to Strings in C++
Bruno Haible
Table of Contents
autosprintf.html#SEC1
1  Introduction
autosprintf.html#SEC2
2  The
autosprintf
class
autosprintf.html#SEC3
3  Using
autosprintf
in own programs
autosprintf.html#TOC1
1  Introduction
This package makes the C formatted output routines (
fprintf
et al.)
usable in C++ programs, for use with the
<string>
strings and the
<iostream>
streams.
It allows to write code like
cerr << autosprintf ("syntax error in %s:%d: %s", filename, line, errstring);
instead of
cerr << "syntax error in " << filename << ":" << line << ": " << errstring;
The benefits of the autosprintf syntax are:
It reuses the standard POSIX printf facility. Easy migration from C to C++.
English sentences are kept together.
It makes internationalization possible. Internationalization requires format
strings, because in some cases the translator needs to change the order of a
sentence, and more generally it is easier for the translator to work with a
single string for a sentence than with multiple string pieces.
It reduces the risk of programming errors due to forgotten state in the
output stream (e.g.
cout << hex;
not followed by
cout << dec;
).
autosprintf.html#TOC2
2  The
autosprintf
class
An instance of class
autosprintf
just contains a string with the
formatted output result. Such an instance is usually allocated as an
automatic storage variable, i.e. on the stack, not with
new
on the
heap.
The constructor
autosprintf (const char *format, ...)
takes a format
string and additional arguments, like the C function
printf
.
Conversions to
char *
and
std::string
are defined that return
the encapsulated string.
The destructor
~autosprintf ()
destroys the encapsulated string.
An
operator <<
is provided that outputs the encapsulated string to the
given
ostream
.
autosprintf.html#TOC3
3  Using
autosprintf
in own programs
To use the
autosprintf
class in your programs, you need to add
#include "autosprintf.h"
using gnu::autosprintf;
to your source code.
The include file defines the class
autosprintf
, in a namespace called
gnu
. The
`using´
statement makes it possible to use the class
without the (otherwise natural)
gnu::
prefix.
When linking your program, you need to link with
libasprintf
, because
that's where the class is defined. In projects using GNU
autoconf
,
this means adding
`AC_LIB_LINKFLAGS([asprintf])´
to
configure.in
or
configure.ac
, and using the @LIBASPRINTF@ Makefile variable that
it provides.
This document was generated on 18 January 2004 using the
http://wwwinfo.cern.ch/dis/texi2html/
texi2html
translator version 1.52a.
