R – trying to copy a char pointer using memcpy, getting an error

ccharmemcpy

so I want to copy a char pointer, asked a friend and he said to use memcpy… so I am trying to do this:

charFilenameAndPath=strtok(filename,".");
memcpy=(charFilename,charFilenameAndPath, sizeof(charFilenameAndPath));

and the compiler is spitting out this:

uTrackSpheres.cpp:176: error: assignment of function ‘void* memcpy(void*, const void*, size_t)’
uTrackSpheres.cpp:176: error: cannot convert ‘unsigned int’ to ‘void*(void*, const void*, size_t)throw ()’ in assignment

I also tried using strlen instead of sizeof

Best Answer

In your second line:

memcpy=(charFilename,charFilenameAndPath, sizeof(charFilenameAndPath));

there is a spurious = sign.

Once you fix that, your call is not correct anyway. charFilenameAndPath is the return value from strtok(), so it must be a char *. So, you are copying sizeof(char *) bytes to charFilename, you probably want strlen(charFilenameAndPath)+1 bytes instead (or you can use strcpy()). In any case, you should make sure that strtok() didn't return NULL and that charFilename has enough space.

Related Solutions

R – How to copy a char[] in c into the struct

currentpkt is of struct type; you need to get a pointer to the struct to get this to work:

memcpy(&currentpkt, recv, bytes);

For your second question, you have some other problems. What if you receive more bytes in a packet than sizeof(struct Packet)? As it's written now, you'll overrun your struct.

What if the client and server applications are compiled using different compilers or settings, or on platforms with different endianness? In this case, the struct might be different sizes on the two platforms and may be laid out in memory differently.

C: byte-copy unsigned char value

Use memcpy. bcopy is only supported on some platforms, and is deprecated in newer standards.

void callback(const unsigned char* data, int len) {
  unsigned char* copydatahere = malloc(len);
  if (!copydatahere) {
    exit(1);
  }
  memcpy(copydatahere, data, len);

  /* ... */

  free(copydatahere);
}

Best Answer

Related Solutions

R – How to copy a char[] in c into the struct

C: byte-copy unsigned char value

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