Reading hex values from a text file - what am I doing wrong?

Hey guys,

I'm trying to read MAC addresses from the following text file:

Code:

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192.168.1.1        00:0c:41:ae:5a:04
192.168.1.103        00:16:76:1d:4d:a9
192.168.90.130        00:0C:29:F2:25:63
192.168.90.131        00:0C:29:C8:D3:9E
192.168.1.104        00:04:75:D5:44:2C

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using the following code:

Code:

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fscanf(database, "%[^\t]\t%02x:%02x:%02x:%02x:%02x:%02x\n", ip_addr, &eth_addr[0], &eth_addr[1], &eth_addr[2], &eth_addr[3], &eth_addr[4], &eth_addr[5])

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However, I'm getting all zeros in the eth_addr array. What am I doing wrong?

How is eth_addr declared?

Quote:

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Originally Posted by Prelude

How is eth_addr declared?

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It is an array of unsigned chars.

Okay, now I'm so desparate I tried the simplest program possible:

Code:

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#include <stdio.h>

int main(void) {
        FILE *f = fopen("test.txt", "r");
        unsigned char test0, test1;
        fscanf(f, "%02x:%02x", &test0, &test1);
        printf("%d %d\n", test0, test1);       
        return (0);
}

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and the test.txt file contains

Code:

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45:68

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The output of the program is "0 104"! I'm totally confused now. By the way, I'm using the gcc compiler on Ubuntu Linux.

>It is an array of unsigned chars.
That's your problem then. scanf expects certain types when you use a format modifier, and %x expects an unsigned int. Failure to meet scanf's expectations will result in wierd things.

Quote:

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Originally Posted by Prelude

>That's your problem then. scanf expects certain types when you use a format modifier, and %x expects an unsigned int. Failure to meet scanf's expectations will result in wierd things.

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Ah, I get it. Thanks a lot!

but then , how is his sample program working? He claims he is getting a non-zero output inspite of declaring test0 and test1 as unsigned chars?

>how is his sample program working?
The result is undefined, so it could be anything.