v7 man page for assert

ASSERT(3X)																ASSERT(3X)

NAME
       assert - program verification

SYNOPSIS
       #include <assert.h>

       assert (expression)

DESCRIPTION
       Assert  is  a  macro that indicates expression is expected to be true at this point in the program.  It causes an exit(2) with a diagnostic
       comment on the standard output when expression is false(0).  Compiling with the cc(1) option -DNDEBUG effectively deletes assert from  the
       program.

DIAGNOSTICS
       `Assertion failed: file f line n.'  F is the source file and n the source line number of the assert statement.

																	ASSERT(3X)