assert(3X)                (Specialized Libraries)                assert(3X)


   NAME
         assert - verify program assertion

   SYNOPSIS
         #include <assert.h>

         void assert (int expression);

   DESCRIPTION
         This macro is useful for putting diagnostics into programs.  When it
         is executed, if expression is false (zero), assert prints

               Assertion failed: expression, file xyz, line nnn

         on the standard error output and aborts.  In the error message, xyz
         is the name of the source file and nnn the source line number of the
         assert statement.  The latter are respectively the values of the
         preprocessor macros __FILE__ and __LINE__.

         Compiling with the preprocessor option -DNDEBUG [see cc(1)], or with
         the preprocessor control statement #define NDEBUG ahead of the
         #include <assert.h> statement, will stop assertions from being
         compiled into the program.

   SEE ALSO
         cc(1), abort(3C).

   NOTES
         Since assert is implemented as a macro, the expression may not
         contain any string literals.























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