Thread: Replace _last_ slash in directory name string

Hey guys,

Hope anyone can help me with my little problem, below.

I've got this string:
./vehicle_database/Ford/Mondeo 2006 Handbrake

(! this is an example, there are many similar strings needed in my program, e.g. ./vehicle_database/Audi/A6 3LV6 Brakelights )


And I want to place a file "one folder up", so in:
./vehicle_database/Ford

My idea was to replace the last forward slash in the first string (after Ford) with a '\0' but I can't get it to work.
I know about strchr, but that only looks for the _first_ time the specified character is in the string.

Code:

      if((p = strchr(data_dir, '/')) != NULL) // search for '/'
      {
         *p = '\0'; // replace / with \0
      }

Am I on the right way? Can I do it with strchr and a special trick, or am I completely wrong? Is there a way for doing this anyway? (of course there is! )

Hope you can help, thanks in advance,


René

If "id_file_array" is an array of characters, then leave off the "[cnt2]". If not, and it's a 2D array, or an array of pointers to characters, then you'r doing it right.

How is 'id_file_array' declared?


Quzah.

Originally Posted by quzah

If "id_file_array" is an array of characters, then leave off the "[cnt2]". If not, and it's a 2D array, or an array of pointers to characters, then you'r doing it right.

How is 'id_file_array' declared?


Quzah.

I'm sorry, I just edited my first post. I took that example from another part of the code. There's no id_file_array[cnt2] involved in this problem. (it's just data_dir, which btw is declared as char data_dir[256])

Well, without using any string functions, you could try something like this, I suppose.

Code:

#include <stdio.h>

int main(void) {
    char pathname[256] = "./vehicle_database/Ford/Mondeo 2006 Handbrake";
    char *charFind = NULL;
    
    printf("%s\n", pathname);
    
    int i;
    for(i = 0; pathname[i] != '\0'; i++)
      if(pathname[i] == '/')
         charFind = &(pathname[i]);
      
    *charFind = '\0';
    
    printf("%s", pathname);

    return 0;
}

I hope there is no real mistakes in there, I'm kinda tired. I did skimp a bit on error checking, though, so you might want to be more careful in a real implementation. You'll likely find a better method using strtok or some other functions, but this should give you an idea of what you *can* do.

EDIT: You might as well use OnionKnight's solution as I need to spruce up on my ANSI C syntax.

Originally Posted by OnionKnight

Replace strchr with strrchr and you've got it!

Heyyy that's perfect, thanks!!

@SlyMaelstrom: what does this part do:

Code:

charFind = &(pathname[i]);

?
I've never seen = &() before.

Originally Posted by rkooij

Heyyy that's perfect, thanks!!

@SlyMaelstrom: what does this part do:

Code:

charFind = &(pathname[i]);

?
I've never seen = &() before.

It's not one operator, the parenthesis just ensures that the subscript operator resolves first, which I'm pretty sure it does anyway, and then I just take the address of that value.

Originally Posted by SlyMaelstrom

... the parenthesis just ensures that the subscript operator resolves first...

Wheeee , I dont understand a WORD of what you just said, haha!

Originally Posted by rkooij

Wheeee , I dont understand a WORD of what you just said, haha!

Alrighty... in &(var[i]) there are three operators. The "address of" operator (&), the "grouping" operator (()), and the "subscript" operator ([]). The grouping operator has the highest precedence of all operators (I believe the subscript operator has the second highest, or possibly the same precedence, but I wanted to be safe) so in order to ensure that the subscript operator is resolved (used/called/happens) first, I grouped it in with the variable and left the third operator & outside to be resolved last. Get it?

Originally Posted by SlyMaelstrom

Alrighty... in &(var[i]) there are three operators. The "address of" operator (&), the "grouping" operator (()), and the "subscript" operator ([]). The grouping operator has the highest precedence of all operators (I believe the subscript operator has the second highest, or possibly the same precedence, but I wanted to be safe) so in order to ensure that the subscript operator is resolved (used/called/happens) first, I grouped it in with the variable and left the third operator & outside to be resolved last. Get it?

Yeah, I get it now! Thanks for explaining inspite of being tired

You're sure you're not a compiler?

Originally Posted by rkooij

Yeah, I get it now! Thanks for explaining inspite of being tired

You're sure you're not a compiler?

Yeah, I'm pretty positive that I could never be mistaken for a C compiler. Though with Miracle C out there, who really knows?

Originally Posted by OnionKnight

Replace strchr with strrchr and you've got it!

Bah. When I read it I read it as strrchr. :P Good catch.


Quzah.