"problems" with strcat

If the data in your arrays has no predictable terminator value (like the null character in C strings), then you'll have to remember the length of the data.

To concatenate, all you have to do is a bit of pointer arithmetic on your destination.

int memcat (U8* dst, int dstLen,
            U8* src, int srcLen)
    {
    return memcpy (dst + dstlen, src, srcLen);
    }

Note that you'd better be sure that dst points to a buffer big enough to hold all this data.

Also remember that adding '1' to a pointer in C adds not one byte to the address, but sizeof(TypePointedTo). So if you have

typedef struct
   {
   ... // various fields here
   } Header;

Header* hdr;

then to point just past the header, you'd say "hdr + 1", not "hdr + sizeof(Header)". Of course, if your TypePointedTo happens to be a byte, then "+ 1" does what you might have expected.

If you like, you can gussy up the basic concept by putting the variables together in a structure.

typedef struct
   {
   int maxLen;
   int curLen;
   U8* data;
   } BoundedArray;

and then write your routines to pass those structures around to appropriate functions built on top of memcpy().

If the data in your arrays has no predictable terminator value (like the null character in C strings), then you'll have to remember the length of the data.

To concatenate, all you have to do is a bit of pointer arithmetic on your destination.

int memcat (U8* dst, int dstLen,
            U8* src, int srcLen)
    {
    return memcpy (dst + dstlen, src, srcLen);
    }

Note that you'd better be sure that dst points to a buffer big enough to hold all this data.

Also remember that adding '1' to a pointer in C adds not one byte to the address, but sizeof(TypePointedTo). So if you have

typedef struct
   {
   ... // various fields here
   } Header;

Header* hdr;

then to point just past the header, you'd say "hdr + 1", not "hdr + sizeof(Header)". Of course, if your TypePointedTo happens to be a byte, then "+ 1" does what you might have expected.

If you like, you can gussy up the basic concept by putting the variables together in a structure.

typedef struct
   {
   int maxLen;
   int curLen;
   U8* data;
   } BoundedArray;

and then write your routines to pass those structures around to appropriate functions built on top of memcpy().