Implementing Chmod command using c

[Shastri]

Hi all,

I was trying to implement chmod command(UNIX) in c. While passing
arguments to the main function like :

-r for reading the file
-w for writing the file


How can I compare the second argument i.e argv[1] with something like
-r?
While running the program if I enter -r it should read the file.
So if(argv[1]=='-r') can't be done as we cant compare a pointer to an
integer. so Please suggest how to do this??


Thanks
Shastri

[Peter Nilsson]

Re: Implementing Chmod command using c

Shastri wrote:[color=blue]
>
> ... While passing arguments to the main function like :
>
> -r for reading the file
> -w for writing the file
>
>
> How can I compare the second argument i.e argv[1] with something like
> -r?[/color]

if (strcmp(argv[1], "-r") == 0)
...

--
Peter

[Ian Collins]

Re: Implementing Chmod command using c

Shastri wrote:[color=blue]
> Hi all,
>
> I was trying to implement chmod command(UNIX) in c. While passing
> arguments to the main function like :
>
> -r for reading the file
> -w for writing the file
>
>
> How can I compare the second argument i.e argv[1] with something like
> -r?
> While running the program if I enter -r it should read the file.
> So if(argv[1]=='-r') can't be done as we cant compare a pointer to an
> integer. so Please suggest how to do this??
>
>[/color]
Check for '-', then test the following character.

--
Ian Collins.

[sathyashrayan]

Re: Implementing Chmod command using c


"Shastri" <sas429s@gmail. com> wrote in message
news:1139187143 .434946.125840@ z14g2000cwz.goo glegroups.com.. .[color=blue]
> Hi all,
>
> I was trying to implement chmod command(UNIX) in c. While passing
> arguments to the main function like :
>
> -r for reading the file
> -w for writing the file
>
>
> How can I compare the second argument i.e argv[1] with something like
> -r?
> While running the program if I enter -r it should read the file.
> So if(argv[1]=='-r') can't be done as we cant compare a pointer to an
> integer. so Please suggest how to do this??
>
>
> Thanks
> Shastri
>
>[/color]


int main(int argc, char *argv[])

In a main() like the above you can use multi dimentation array
such as ,argv[rows][coloums] along with counter argc inside a if statement.
Simply use loop iterations for rows and coloums to march through the array.
Hope that helps.

[Barry Schwarz]

Re: Implementing Chmod command using c

On 5 Feb 2006 16:52:23 -0800, "Shastri" <sas429s@gmail. com> wrote:
[color=blue]
>Hi all,
>
>I was trying to implement chmod command(UNIX) in c. While passing
>arguments to the main function like :
>
>-r for reading the file
>-w for writing the file
>
>
>How can I compare the second argument i.e argv[1] with something like
>-r?
>While running the program if I enter -r it should read the file.
>So if(argv[1]=='-r') can't be done as we cant compare a pointer to an
>integer. so Please suggest how to do this??[/color]

You are looking for the strcmp function.

BTW, '-r' is a no-no. The ' delimiter is for a character constant
containing a single character. You want "-r" which defines a string
literal.[color=blue]
>
>
>Thanks
>Shastri[/color]
Remove del for email

[Mark B]

Re: Implementing Chmod command using c


"Barry Schwarz" <schwarzb@doezl .net> wrote in message
news:ucufu15lp9 cckkt67grup5ti6 vck3vohoq@4ax.c om...[color=blue]
> On 5 Feb 2006 16:52:23 -0800, "Shastri" <sas429s@gmail. com> wrote:
>[color=green]
>>Hi all,
>>
>>I was trying to implement chmod command(UNIX) in c. While passing
>>arguments to the main function like :
>>
>>-r for reading the file
>>-w for writing the file
>>
>>
>>How can I compare the second argument i.e argv[1] with something like
>>-r?
>>While running the program if I enter -r it should read the file.
>>So if(argv[1]=='-r') can't be done as we cant compare a pointer to an
>>integer. so Please suggest how to do this??[/color]
>
> You are looking for the strcmp function.
>
> BTW, '-r' is a no-no. The ' delimiter is for a character constant
> containing a single character. You want "-r" which defines a string
> literal.[/color]

Yeah, I don't think that will work too well either as written...
How about: if(strcmp(argv[1], "-r") == 0)
or better yet, use getopt() if it's available on your platform.

Mark