assert(3X)              LIBRARY FUNCTIONS              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  mes-
     sage,  xyz is the name of the source file and nnn the source
     line number of the assert statement.  The latter are respec-
     tively  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 asser-
     tions 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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