How to create a byte array in C

Question

Please have a look at the followng header file   pragma once  class MissileLauncher   public      MissileLauncher void    private      byte abc 3        This generated the error  Error   1   error C2143  syntax error   missing     before         I tried to do it in this way  byte  abc    but it also failed  same error  However  I noticed I can call other built in tyes arrays in this way for an example  an int array  Why this is happening to byte array  How to solve this  I would like to assign the values in cpp file  Any ideas

User · Answer

Byte is not a standard data type in C C   but it can still be used the way i suppose you want it  Here is how  Recall that a byte is an eight bit memory size which can represent any of the integers between -128 and 127  inclusive   There are 256 integers in that range  eight bits can represent 256 -- two raised to the power eight -- different values    Also recall that a char in C C   is one byte  eight bits   So  all you need to do to have a byte data type in C C   is to put this code at the top of your source file       define byte char So you can now declare     byte abc 3

User · Answer

Byte is not a standard type in C C    so it is represented by char   An advantage of this is that you can treat a basic string as a byte array allowing for safe storage and function passing  This will help you avoid the memory leaks and segmentation faults you might encounter when using the various forms of char   and char    For example  this creates a string as a byte array of null values   typedef basic string lt unsigned char gt  u string   u string bytes   u string 16   0      This allows for standard bitwise operations with other char values  including those stored in other string variables  For example  to XOR the char values of another u string across bytes   u string otherBytes    some more chars  which are just bytes   for int i   0  i  lt  otherBytes length    i        bytes i 16      int otherBytes i

User · Answer

If you want exactly one byte  uint8 t defined in cstdint would be the most expressive   http   www cplusplus com reference cstdint

User · Answer

Byte is not a standard type in C or C     Try char  which is usually and at least 8 bits long

User · Answer

You could use Qt which  in case you don t know  is C   with a bunch of additional libraries and classes and whatnot  Qt has a very convenient QByteArray class which I m quite sure would suit your needs   http   qt-project org

User · Answer

Try  class MissileLauncher   public      MissileLauncher void    private      unsigned char abc 3        or  using byte   unsigned char   class MissileLauncher   public      MissileLauncher void    private      byte abc 3          Note  In older compilers  non-C  11  replace the using line with typedef unsigned char byte

User · Answer

Maybe you can leverage the std  bitset type available in C  11  It can be used to represent a fixed sequence of N bits  which can be manipulated by conventional logic    include lt iostream gt   include lt bitset gt   class MissileLauncher    public    MissileLauncher        void show bits   const       std  cout lt  lt m abc 2  lt  lt      lt  lt m abc 1  lt  lt      lt  lt m abc 0  lt  lt std  endl         bool toggle a            toggles  i e   flips  the value of  a  bit and returns the        resulting logical value     m abc 0  flip        return m abc 0          bool toggle c            toggles  i e   flips  the value of  c  bit and returns the        resulting logical value     m abc 2  flip        return m abc 2          bool matches const std  bitset lt 3 gt  amp  mask           tests whether all the bits specified in  mask  are turned on in        this instance s bitfield     return   m abc  amp  mask     mask         private    std  bitset lt 3 gt  m abc      typedef std  bitset lt 3 gt  Mask  int main       MissileLauncher ml        notice that the bitset can be  built  from a string - this masks      can be made available as constants to test whether certain bits      or bit combinations are  on  or  off    Mask has a  001             the zeroth bit   Mask has b  010             the first bit   Mask has c  100             the second bit   Mask has a and c  101       zeroth and second bits   Mask has all on  111        all on    Mask has all off  000       all off        I can even create masks using standard logic  in this case I use      the or     operator    Mask has a and b   has a   has b    std  cout lt  lt  This should be 011    lt  lt has a and b lt  lt std  endl        print  true  and  false  instead of  1  and  0    std  cout lt  lt std  boolalpha     std  cout lt  lt  Bits  as created  lt  lt std  endl    ml show bits      std  cout lt  lt  is a turned on    lt  lt ml matches has a  lt  lt std  endl    std  cout lt  lt  I will toggle a  lt  lt std  endl    ml toggle a      std  cout lt  lt  Resulting bits   lt  lt std  endl    ml show bits        std  cout lt  lt  is a turned on now    lt  lt ml matches has a  lt  lt std  endl    std  cout lt  lt  are both a and c on    lt  lt ml matches has a and c  lt  lt std  endl    std  cout lt  lt  Toggle c  lt  lt std  endl    ml toggle c      std  cout lt  lt  Resulting bits   lt  lt std  endl    ml show bits          std  cout lt  lt  are both a and c on now    lt  lt ml matches has a and c  lt  lt std  endl      std  cout lt  lt  but  are all bits on    lt  lt ml matches has all on  lt  lt std  endl    return 0      Compiling using gcc 4 7 2  g   example cpp -std c  11   I get   This should be 011  011 Bits  as created false  false  false is a turned on  false I will toggle a Resulting bits  false  false  true is a turned on now  true are both a and c on  false Toggle c Resulting bits  true  false  true are both a and c on now  true but  are all bits on  false

[c++] How to create a byte array in C++?

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