Re: strings and NULL argument passing

James Kanze <>
Thu, 13 Nov 2008 13:48:44 -0800 (PST)
On Nov 13, 9:00 pm, Jeff Schwab <> wrote:

Make a version of print() which takes a const char* as
parameter and performs the check. If a non-null pointer is
passed, it simply calls the print() taking a std::string as
parameter, else it performs whatever error termination you
want (eg. assert()).

"assert" means "I know this is true." It's enforced
documentation, not a general-purpose way to terminate a

Anyway, there's nothing here that implies termination. An
exception can be thrown, or the null pointer can just be
accepted as an empty string, or a C-style error code can be
returned. In my experience, the exception is usually the
right way to go.

A null pointer is not a string (in the general sense), nor is it
something which can be converted into a string. If his
interface requires a string, then passing it a null pointer
should cause an assertion failure. If his interface supports
the idea of a nullable string (e.g. something you might get when
reading a VARCHAR field from a database), then it has to support
something more than std::string.

James Kanze (GABI Software)
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