CODEWITHSUNDEEP
chexarrays
Errtu
Errtu

Reputation: 45

Creating a char array using hex values

I've got a quick question to someone that knows their way around C - I'm trying to save a char array using hex values, so it looks like this :

char string[84]={0x32,0x51,0x0b,0xa9,0xba,0xbe,0xbb,0xbe,0xfd,0x00,0x15,0x47,0xa8,0x10,0xe6,0x71,0x49,0xca,0xee,0x11,0xd9,0x45,0xcd,0x7f,0xc8,0x1a,0x05,0xe9,0xf8,0x5a,0xac,0x65,0x0e,0x90,0x52,0xba,0x6a,0x8c,0xd8,0x25,0x7b,0xf1,0x4d,0x13,0xe6,0xf0,0xa8,0x03,0xb5,0x4f,0xde,0x9e,0x77,0x47,0x2d,0xbf,0xf8,0x9d,0x71,0xb5,0x7b,0xdd,0xef,0x12,0x13,0x36,0xcb,0x85,0xcc,0xb8,0xf3,0x31,0x5f,0x4b,0x52,0xe3,0x01,0xd1,0x6e,0x9f,0x52,0xf9,0x04};

so basically when I output it using for example something like 

for (i=0;i<string_len;i++)
        printf("%d \t---\t %x\n",i,cipher_11[i]);

I'd expect to get the same values, just without the 0x in front and it does work for most of those values, some of them however have "ffff" in front which kind of breaks the rest of my program :) Kind of a newbie in hex operations so I'm pretty sure I'm doing something very silly. Any hints ? (btw the output looks like the picture : http://postimg.org/image/k0npwh9a5/ )

Upvotes: 2

Views: 5603

Answers (1)

paddy
paddy

Reputation: 63471

Some of your characters have their most significant bit set, and so would represent a negative value (assuming your compiler treats char as a signed value). So when it is implicitly cast as an integer (during the call to printf), it will be interpreted as a negative value. This is the case for all values larger than 0x7f.

You should either declare cipher_11 as unsigned char, or cast the value during printf:

printf("%d \t---\t %x\n", i, (unsigned char)cipher_11[i]);

Upvotes: 5

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