C - get chars from part of byte array

Question

How can I get char array or char pointer from part of byte array? Let´s say I have variable-size string in byte array which begins at 18 bytes and ends 4 bytes from end of array. How can I get this?

Edit: And what about dot? I should have dots in that byte array but when I copied by memcpy I get string without dots. How can I fix this?

Answer 1

To extract a part of an array, you can use memcpy.

#include <string.h>

char dst[4];

/* Here, we can assume `src+18` and `dst` don't overlap. */
memcpy(dst, src + 18, 4);

C11 (n1570), § 7.24.2.1 The memcpy function
The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. If copying takes place between objects that overlap, the behavior is undefined.