vsprintf(3) [osf1 man page]
vprintf(3) Library Functions Manual vprintf(3) NAME
vprintf, vfprintf, vsnprintf, vsprintf - Format a variable number of parameters for output LIBRARY
Standard C Library (libc.so, libc.a) SYNOPSIS
#include <stdarg.h> #include <stdio.h> int vprintf( const char *format, va_list printarg); int vfprintf( FILE *stream, const char *format, va_list printarg); int vsnprintf( char *string, size_t n, const char *format, va_list printarg); int vsprintf( char *string, const char *format, va_list printarg); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: vfprintf(), vprintf(), vsnprintf(), vsprintf(): ISO C, XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Specifies a character string that contains two types of objects: Plain characters, which are copied to the output stream. Conversion spec- ifications, each of which causes zero or more items to be fetched from the stdarg parameter lists. Specifies the arguments to be printed. Specifies the output stream. Specifies the buffer to which output is printed. Specifies the size of the buffer referred to by string. DESCRIPTION
The vprintf(), vfprintf(), vsnprintf(), and vsprintf() functions format and write stdarg parameter lists. These functions are the same as the printf(), fprintf(), snprintf(), and sprintf() functions, respectively, except that these functions are not called with a variable number of parameters. Instead, vprintf(), vfprintf(), vsnprintf(), and vsprintf() are called with a parameter list pointer as defined by stdarg. Because these functions invoke the va_arg() macro and not the va_end() macro, the value of printarg is indeterminate after a return. Therefore, applications should execute a call to the va_end() macro after a call to one of these functions. EXAMPLES
The following example demonstrates how the vfprintf() function can be used to write an error routine: #include <stdarg.h> #include <stdio.h> void error(char *funct, char *fmt, ...) { va_list args; /* ** Display the name of the function that called error */ fprintf(stderr, "ERROR in %s: ", funct); /* ** Display the remainder of the message */ va_start(args, fmt); vfprintf(stderr, fmt, args); va_end(args); abort(); } RELATED INFORMATION
Functions: fopen(3), printf(3), vwprintf(3), wprintf(3) delim off vprintf(3)
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vprintf(3C) Standard C Library Functions vprintf(3C) NAME
vprintf, vfprintf, vsprintf, vsnprintf - print formatted output of a variable argument list SYNOPSIS
#include <stdio.h> #include <stdarg.h> int vprintf(const char *format, va_list ap); int vfprintf(FILE *stream, const char *format, va_list ap); int vsprintf(char *s, const char *format, va_list ap); int vsnprintf(char *s, size_t n, const char *format, va_list ap); DESCRIPTION
The vprintf(), vfprintf(), vsprintf() and vsnprintf() functions are the same as printf(), fprintf(), sprintf(), and snprintf(), respec- tively, except that instead of being called with a variable number of arguments, they are called with an argument list as defined in the <stdarg.h> header. See printf(3C). The <stdarg.h> header defines the type va_list and a set of macros for advancing through a list of arguments whose number and types may vary. The argument ap to the vprint family of functions is of type va_list. This argument is used with the <stdarg.h> header file macros va_start(), va_arg(), and va_end() (see stdarg(3EXT)). The EXAMPLES section below demonstrates the use of va_start() and va_end() with vprintf(). The macro va_alist() is used as the parameter list in a function definition, as in the function called error() in the example below. The macro va_start(ap, parmN), where ap is of type va_list and parmN is the rightmost parameter (just before ...), must be called before any attempt to traverse and access unnamed arguments is made. The va_end(ap) macro must be invoked when all desired arguments have been accessed. The argument list in ap can be traversed again if va_start() is called again after va_end(). In the example below, the error() arguments (arg1, arg2, ...) are passed to vfprintf() in the argument ap. RETURN VALUES
Refer to printf(3C). ERRORS
The vprintf() and vfprintf() functions will fail if either the stream is unbuffered or the stream's buffer needed to be flushed and: EFBIG The file is a regular file and an attempt was made to write at or beyond the offset maximum. EXAMPLES
Example 1: Using vprintf() to write an error routine. The following demonstrates how vfprintf() could be used to write an error routine: #include <stdio.h> #include <stdarg.h> . . . /* * error should be called like * error(function_name, format, arg1, ...); */ void error(char *function_name, char *format, ...) { va_list ap; va_start(ap, format); /* print out name of function causing error */ (void) fprintf(stderr, "ERR in %s: ", function_name); /* print out remainder of message */ (void) vfprintf(stderr, format, ap); va_end(ap); (void) abort(); } ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |See below. | +-----------------------------+-----------------------------+ The vprintf() and vfprintf() functions are MT-Safe. The vsprintf() and vsnprintf() functions are Async-Signal-Safe. SEE ALSO
printf(3C), attributes(5), stdarg(3EXT), attributes(5), standards(5) NOTES
The vsnprintf() return value when n = 0 was changed in the Solaris 10 release. The change was based on the SUSv3 specification. The previ- ous behavior was based on the initial SUSv2 specification, where vsnprintf() when n = 0 returns an unspecified value less than 1. SunOS 5.10 29 Mar 2004 vprintf(3C)