Re: A question regarding C string functions

On 4/2/25 14:11, Lew Pitcher wrote:

I cannot find any definitive statement in my copies of the various
C language standards that addresses the behaviour of the C string
functions when given a NULL pointer.
>
Specifically, what does the C standard dictate about the behaviour of
strrchr(NULL,'/')
but the question could apply to any of the string functions
(strlen(NULL), etc.)
>
My gut impression is that
strrchr(NULL,'/'), etc
invoke undefined behaviour, and should be avoided.
>
Can anyone comment?
>

In n3096.pdf (dated )
"If an argument to a function has an invalid value (such as a value
outside the domain of the function, or a pointer outside the address
space of the program, or a null pointer, or a pointer to non-modifiable
storage when the corresponding parameter is not const-qualified) or a
type (after default argument promotion) not expected by a function with
a variable number of arguments, the behavior is undefined." (7.1.4p1)

But keep in mind that this general rule can be overridden by explict
statements defining the behavior of a function when passed a null
pointer. Such statements occur in the descriptions of a dozens of
functions. I started compiling a list, but gave up.