Extracting certain bits from sequence of bits

[lucaspewkas]

OK so I have a char* variable, which contains the header for a particular packet. There are various fields in this packet but the header isn't split up into different variables. So my question is, how do I extract a hex number from this sequence of bits?

i.e. if header = 02C0001400F00000
and I need header[4-8] = 0014
so I can convert it into decimal 20 using strtol

Thanks for any help!

-Luke

[Dave_Sinkula]

Point to the start of your long with the first parameter to strtol.

[lucaspewkas]

But wouldn't that convert the entire string after that element? I need it to stop at header[8]. And also how do you point to an element within an array? Because if I just put header[4] as the first argument, it would obviously only convert the one bit.

[Dave_Sinkula]

I really don't care to always come up with special-purpose examples when that is within the grasp of the OP, but if you are willing to indulge me and wait a bit I'll edit one in.

[edit]My bad. It's late.

#include <stdio.h>

int main (void)
{
   const unsigned char buffer[] = {0x02,0xC0,0x00,0x14,0x00,0xF0,0x00,0x00};
   unsigned short value = (buffer[2] << 8) | buffer[3];
   printf("value = &#37;hu\n", value);
   return 0;
}

[lucaspewkas]

ummm, well I'm willing to wait, but I'll work it out myself if you don't want to, was just trying to save a bit of time...

[lucaspewkas]

Thank you It's a big help