c programming put a hexa into char

Question

I have

    unsigned char src_mac[6];

that holds values with the %02x format.For example to find the value in src_mac[0] i do:

    printf("%02x\n",src_mac[0]);

I want to know how to put values in src_mac(I need to put a mac adress saved as a string into src_mac and then put the mac adress into a ether_arp structure.

`scanf` is what you're looking for. – Flexo Jan 26 '13 at 15:24 — Flexo, Jan 26 '13 at 15:24
I don't read the mac from the keyboard – Emil Grigore Jan 26 '13 at 15:30 — Emil Grigore, Jan 26 '13 at 15:30
ok, `sscanf` if it's a string and not from stdin. – Flexo Jan 26 '13 at 15:32 — Flexo, Jan 26 '13 at 15:32

Davide Berra · Accepted Answer · 2013-01-26T16:09:43.823

1

Editing my answer... i misread it

Anyway, try this sscanf with hhx as parameters... it means it will read an hex value and will store it as a char (unlikely the default that store the value as int)

sscanf(string_mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", &src_mac[5], &src_mac[4], &src_mac[3], 
                                                    &src_mac[2], &src_mac[1], &src_mac[0]);

edited Jan 26 '13 at 16:09

answered Jan 26 '13 at 15:31

Davide Berra

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hi.I know how to memcpy,I just don't know how to fill the unsigned char array used for memcpy(src_mac) – Emil Grigore Jan 26 '13 at 15:39
I get the warning format '%x' expects argument of type int but the argument is of type 'unsigned char *' – Emil Grigore Jan 26 '13 at 15:58
@Emil is damn right... i updated the answer to make scanf read an hex and put it into a uint8_t – Davide Berra Jan 26 '13 at 16:10

c programming put a hexa into char

1 Answers1