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.\"   Copyright (c) 1994-2006 Lars Wirzenius.  All rights reserved.
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.\" part of publib
.\" "@(#)publib-strutil:$Id: strvars.3,v 1.2 1995/06/17 10:47:23 wirzeniu Exp $"
.\"
.TH STRVARS 3pub "C Programmer's Manual" Publib "C Programmer's Manual"
.SH NAME
strvars \- expand variables in string
.SH SYNOPSIS
.nf
#include <publib.h>
int \fBstrvars\fR(char **\fIres\fR, const char *\fIstr\fR, char *(*\fIexpand\fR)(const char *));
.SH DESCRIPTION
\fIstrvars\fR will replaces references to variables in the string \fIstr\fR
with the values of the variables.  A reference to a variable 
is of the form \fI$(foo)\fR or \fI$x\fR (where \fIx\fR is a single
character, but not \fI$\fR).  A dollar sign is expressed in the string
as \fI$$\fR, and will be converted to \fI$\fR in the output.  Memory
for the expanded string is allocated dynamically, and \fI*res\fR is set
to point to it.
.PP
The values of the variables are fetched using the function \fIexpand\fR.
It is given the name of the variable as its argument, and must return
a pointer to the value, or NULL if that variable doesn't exist.
.SH "RETURN VALUE"
\fIstrvars\fR will return 0 if successful, or NULL if an
error occurred (malformed input string, result too big, or unknown variable).
.SH EXAMPLE
To replace references to environment variables, one would the following.
.sp 1
.nf
.in +5
#include <publib.h>
#include <stdlib.h>

char line[1024];
char *res;

if (strvars(&res, line, getenv) == NULL)
    errormsg(1, 0, "strvars failed");
printf("res = <%s>\\n", res);
.in -5
.SH "SEE ALSO"
publib(3), getenv(3)
.SH AUTHOR
Lars Wirzenius (lars.wirzenius@helsinki.fi)