.TH LIBNORMALFORM_EVALUATE 3 LIBNORMALFORM
.SH NAME
libnormalform_evaluate \- Determine value of a formula

.SH SYNOPSIS
.nf
#include <libnormalform.h>

int libnormalform_evaluate(LIBNORMALFORM_SENTENCE *\fIformula\fP);
.fi
.PP
Link with
.IR -lnormalform .

.SH DESCRIPTION
The
.BR libnormalform_evaluate ()
function determines the value of
.IR formula .
.PP
Before calling the
.BR libnormalform_evaluate ()
function, the application must configure application
defined parts of the formula. That is, any
.IR "struct libnormalform_variable" ,
.IR "struct libnormalform_function" ,
.IR "struct libnormalform_map" ,
and
.IR "struct libnormalform_transformer"
must be set configuared accord to the specifications
specified for the function it was used in.

.SH RETURN VALUE
Upon successful completion, the
.BR libnormalform_evaluate ()
function returns 1 if the
.I formula
is true for configured input, 0 if the
.I formula
is false for configured input;
otherwise, the function returns
.IR -1 .

.SH ERRORS
The
.BR libnormalform_evaluate ()
function fails if an application function fails.
The
.BR libnormalform_evaluate ()
function does not modify
.IR errno ,
but lets application functions modify
.IR errno .

.SH ATTRIBUTES
For an explanation of the terms used in this
section, see
.BR attributes (7)
and
.IR "info \(dq(libc)POSIX Safety Concepts\(dq" .
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR libnormalform_evaluate ()
T}	Thread safety	MT-Safe race:\fIsentence\fP
T{
.BR libnormalform_evaluate ()
T}	Async-signal safety	AS-Unsafe heap
T{
.BR libnormalform_evaluate ()
T}	Async-cancel safety	AC-Safe mem, AC-Unsafe heap
.TE

.SH SEE ALSO
.BR libnormalform (7)