Re: The type of argv in K&R2

[Joe Wright]

candide wrote:

Hi,
>
K&R2 §5.10 tells that the second parameter to the main function,
usually called argv, has type pointer to character strings.
>
Some quotes from the book :
>
>
-------------------- 8< ----------------------------------------
"the second (argv, for argument vector) is a pointer to an array of
character strings"
>
"Since argv is a pointer to an array of pointers,"
>
"Since argv is a pointer to the beginning of the array of argument strings"
-------------------- >8 ----------------------------------------
>
>
In fact, argv is rather an array of strings, as explained in the
preceding § :
>
>
-------------------- 8< ----------------------------------------
"Compare the declaration and picture for an array of pointers:
char *name[] = { "Illegal month", "Jan", "Feb", "Mar" };"
-------------------- >8 ----------------------------------------
>
>
Right ?
>
Thanks

Nope. It is most correctly 'char **argv', pointer to pointer to char.
Declaring 'char *argv[]' is exactly equivalent. It says argv is an array
of pointers to char. Expressing argv as an array yields a pointer to its
first element.

I believe 'array of strings' is misleading. It is 'array of pointer to
char' in fact.

--
Joe Wright
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

[CBFalconer]

Re: The type of argv in K&amp;R2

Joe Wright wrote:

>

.... snip ...

>
Nope. It is most correctly 'char **argv', pointer to pointer to
char. Declaring 'char *argv[]' is exactly equivalent. It says
argv is an array of pointers to char. Expressing argv as an array
yields a pointer to its first element.
>
I believe 'array of strings' is misleading. It is 'array of
pointer to char' in fact.

However those pointers have been initialized to point to arrays of
char, and each array of char has been filled with a '\0' terminated
string. The first pointer (the 0th) points to a string describing
the running program iff that information is available else an empty
string, and the argcth points to a NULL pointer, marking the end of
the list.

Note the difference between a pointer to an empty string (no data)
and a NULL, which marks the list end.

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.


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[Barry Schwarz]

Re: The type of argv in K&amp;R2

On Sun, 22 Jun 2008 20:44:35 -0400, CBFalconer <cbfalconer@yah oo.com>
wrote:

>Joe Wright wrote:

>>

>... snip ...

>>
>Nope. It is most correctly 'char **argv', pointer to pointer to
>char. Declaring 'char *argv[]' is exactly equivalent. It says
>argv is an array of pointers to char. Expressing argv as an array
>yields a pointer to its first element.
>>
>I believe 'array of strings' is misleading. It is 'array of
>pointer to char' in fact.

>
>However those pointers have been initialized to point to arrays of
>char, and each array of char has been filled with a '\0' terminated
>string. The first pointer (the 0th) points to a string describing
>the running program iff that information is available else an empty
>string, and the argcth points to a NULL pointer, marking the end of
>the list.

Of course you meant the argcth *is* a NULL pointer.

>
>Note the difference between a pointer to an empty string (no data)
>and a NULL, which marks the list end.

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