assert(3)

NAME
     assert - program verification

SYNOPSIS
     #include <assert.h>

     void assert(int expression)

DESCRIPTION
     Assert is a macro that indicates expression is expected  to  be  true  at
     this  point  in  the  program.   It  causes an abort(3) 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 "expression" failed: file f line n.'  F is the source file and
     n the source line number of the assert statement.