'\" t
.\"     Title: vsnprintf
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: June 2017
.\"    Manual: Basic C Library Functions
.\"    Source: Kernel Hackers Manual 4.11.3
.\"  Language: English
.\"
.TH "VSNPRINTF" "9" "June 2017" "Kernel Hackers Manual 4\&.11\&" "Basic C Library Functions"
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.SH "NAME"
vsnprintf \- Format a string and place it in a buffer
.SH "SYNOPSIS"
.HP \w'int\ vsnprintf('u
.BI "int vsnprintf(char\ *\ " "buf" ", size_t\ " "size" ", const\ char\ *\ " "fmt" ", va_list\ " "args" ");"
.SH "ARGUMENTS"
.PP
\fIchar * buf\fR
.RS 4
The buffer to place the result into
.RE
.PP
\fIsize_t size\fR
.RS 4
The size of the buffer, including the trailing null space
.RE
.PP
\fIconst char * fmt\fR
.RS 4
The format string to use
.RE
.PP
\fIva_list args\fR
.RS 4
Arguments for the format string
.RE
.SH "DESCRIPTION"
.PP
This function generally follows C99 vsnprintf, but has some extensions and a few limitations:
.PP
\fBn\fR
is unsupported
\fBp\fR* is handled by
\fBpointer\fR
.PP
See
\fBpointer\fR
or Documentation/printk\-formats\&.txt for more extensive description\&.
.PP
** Please update the documentation in both places when making changes **
.PP
The return value is the number of characters which would be generated for the given input, excluding the trailing \*(Aq\e0\*(Aq, as per ISO C99\&. If you want to have the exact number of characters written into
\fIbuf\fR
as return value (not including the trailing \*(Aq\e0\*(Aq), use
\fBvscnprintf\fR\&. If the return is greater than or equal to
\fIsize\fR, the resulting string is truncated\&.
.PP
If you\*(Aqre not already dealing with a va_list consider using
\fBsnprintf\fR\&.
.SH "COPYRIGHT"
.br