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.Dd May 15, 2003
.Os
.Dt CTASSERT 9
.Sh NAME
.Nm CTASSERT
.Nd compile time assertion macro
.Sh SYNOPSIS
.Pp
.In sys/param.h
.In sys/systm.h
.Fn CTASSERT expression
.Sh DESCRIPTION
The
.Nm
macro evaluates
.Fa expression
at compile time and causes a compiler error if it is false.
.Pp
The
.Nm
macro is useful for asserting the size or alignment of important
data structures and variables during compilation, which would
otherwise cause the code to fail at run time.
.Sh EXAMPLES
Assert that the size of the
.Vt uuid
structure is 16 bytes.
.Bd -literal -offset indent
CTASSERT(sizeof(struct uuid) == 16);
.Ed
.Sh SEE ALSO
.Xr KASSERT 9
.Sh AUTHORS
This manual page was written by
.An Hiten M. Pandya
.Aq hmp@FreeBSD.ORG .