Variable and pointer

[Julia]

I am a n00b to c, so have pitty on me if I ask dumb questions .
I have a function (testframe() ) that has needs a pointer to a 6 byte MAC
address as input. The input is an unsigned 8 bit char pointer.
This pointer should then point to the 6 byte MAC address stored somewhere.
How do I actually write this in code? An integer is only 32 bit, so how do I
have something holding the MAC Address and more again, how do I create a
pointer pointing to this "something".

Julia

 

[Dan Pop]

I am a n00b to c, so have pitty on me if I ask dumb questions .
I have a function (testframe() ) that has needs a pointer to a 6 byte MAC
address as input. The input is an unsigned 8 bit char pointer.
This pointer should then point to the 6 byte MAC address stored somewhere.
How do I actually write this in code? An integer is only 32 bit, so how do I
have something holding the MAC Address and more again, how do I create a
pointer pointing to this "something".

unsigned char macaddr[6], *p = macaddr;

Dan

 

[Kevin Easton]

I am a n00b to c, so have pitty on me if I ask dumb questions .
I have a function (testframe() ) that has needs a pointer to a 6 byte MAC
address as input. The input is an unsigned 8 bit char pointer.
This pointer should then point to the 6 byte MAC address stored somewhere.
How do I actually write this in code? An integer is only 32 bit, so how do I
have something holding the MAC Address and more again, how do I create a
pointer pointing to this "something".

unsigned char mac[6] = { 0x00, 0xC0, 0x4F, 0xDD, 0xB8, 0x73 };

then just pass "mac". An array (like "mac") is evaluated as a pointer
to its first subobject unless it is the operand of unary-& or sizeof, so
you don't need to do anything special to create the pointer.

- Kevin.

 

[Thomas Matthews]

I am a n00b to c, so have pitty on me if I ask dumb questions .
I have a function (testframe() ) that has needs a pointer to a 6 byte MAC
address as input. The input is an unsigned 8 bit char pointer.
This pointer should then point to the 6 byte MAC address stored somewhere.
How do I actually write this in code? An integer is only 32 bit, so how do I
have something holding the MAC Address and more again, how do I create a
pointer pointing to this "something".

Julia

Most applications treat MAC addresses as a collection of
octects (bytes). Just access it via pointer to unsigned
char. If the processor wants to promote the 8-bit u.c.
to a 32-bit unsigned integer, let it. Some processors
actually fetch the 8 bits into a 32-bit register.

If you need more help, please post a code fragment
demonstrating what you are doing.