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]

... 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?

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

 

[Ian Collins]

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??

Check for '-', then test the following character.

 

[sathyashrayan]

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

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]

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??

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.

Thanks
Shastri

Remove del for email

 

[Mark B]

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??

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.

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