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📖 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;

Benefits:

• 🔄 Reuses standard POSIX printf facility. Easy migration from C to C++.
• 💬 English sentences are kept together.
• 🌐 Makes internationalization possible (format strings allow translator to reorder sentence).
• 🛡️ Reduces risk of programming errors due to forgotten stream state (e.g., cout << hex; without cout << dec;).

🚀 Quick Reference

Use Case	Command	Description
📝 Format a string with printf-like syntax	autosprintf(format, ...)	Returns a std::string with formatted output.
🔗 Output to stream	stream << autosprintf(...)	Uses operator<< to insert formatted string into an ostream.
📄 Convert to C string	(char *)autosprintf(...)	Returns a freshly allocated copy (must be freed with delete[]).
🔧 Include in source	#include "autosprintf.h"	Include the class definition.
🔗 Use namespace	using gnu::autosprintf;	Allows use without gnu:: prefix.
📦 Link with library	-lasprintf or @LIBASPRINTF@	Link against libasprintf.

🏷️ Class autosprintf

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 (on the stack), not with new on the heap.

• Constructor: autosprintf (const char *format, ...) — takes a format string and additional arguments, like C printf.
• Conversions:
  • To char * — returns a freshly allocated copy (must be freed with delete[]).
  • To std::string — returns a copy with automatic memory management.
• Destructor: ~autosprintf () — destroys the encapsulated string.
• Output operator: operator << — outputs the encapsulated string to the given ostream.

🔧 Using autosprintf in own programs

To use the autosprintf class, add to your source code:

#include "autosprintf.h"
using gnu::autosprintf;

The include file defines the class in namespace gnu. The using statement allows use without the gnu:: prefix.

When linking, link with libasprintf. In projects using GNU autoconf, add AC_LIB_LINKFLAGS([asprintf]) to configure.in or configure.ac, and use the @LIBASPRINTF@ Makefile variable.

📄 Licenses

The files of this package are covered by the licenses indicated in each particular file or directory. Summary:

• libasprintf library — GNU Lesser General Public License (LGPL), version 2.1 or later.
• This manual — Dual licensed under GNU FDL and GNU GPL. See the respective licenses below.

🔗 GNU Lesser General Public License

Version 2.1, February 1999. Copyright (C) 1991, 1999 Free Software Foundation, Inc.

This is the first released version of the Lesser GPL. It is the successor of the GNU Library Public License, version 2.

Full license text: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html

🔗 GNU General Public License

Version 2, June 1991. Copyright (C) 1989, 1991 Free Software Foundation, Inc.

Full license text: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html

🔗 GNU Free Documentation License

Version 1.2, November 2002. Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.

Full license text: https://www.gnu.org/licenses/old-licenses/fdl-1.2.html

📖 Introduction 🚀 Quick Reference 🏷️ Class autosprintf 🔧 Using autosprintf in own programs 📄 Licenses