Is the size of C int 2 bytes or 4 bytes

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Does an Integer variable in C occupy 2 bytes or 4 bytes  What are the factors that it depends on   Most of the textbooks say integer variables occupy 2 bytes  But when I run a program printing the successive addresses of an array of integers it shows the difference of 4

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The answer to this question depends on which platform you are using.
But irrespective of platform, you can reliably assume the following types:

 [8-bit] signed char: -127 to 127
 [8-bit] unsigned char: 0 to 255
 [16-bit]signed short: -32767 to 32767
 [16-bit]unsigned short: 0 to 65535
 [32-bit]signed long: -2147483647 to 2147483647
 [32-bit]unsigned long: 0 to 4294967295
 [64-bit]signed long long: -9223372036854775807 to 9223372036854775807
 [64-bit]unsigned long long: 0 to 18446744073709551615

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This is one of the points in C that can be confusing at first  but the C standard only specifies a minimum range for integer types that is guaranteed to be supported  int is guaranteed to be able to hold -32767 to 32767  which requires 16 bits  In that case  int  is 2 bytes  However  implementations are free to go beyond that minimum  as you will see that many modern compilers make int 32-bit  which also means 4 bytes pretty ubiquitously    The reason your book says 2 bytes is most probably because it s old   At one time  this was the norm  In general  you should always use the sizeof operator if you need to find out how many bytes it is on the platform you re using   To address this  C99 added new types where you can explicitly ask for a certain sized integer  for example int16 t or int32 t   Prior to that  there was no universal way to get an integer of a specific width  although most platforms provided similar types on a per-platform basis

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The only guarantees are that char must be at least 8 bits wide  short and int must be at least 16 bits wide  and long must be at least 32 bits wide  and that sizeof  char   lt   sizeof  short   lt   sizeof  int   lt   sizeof  long   same is true for the unsigned versions of those types      int may be anywhere from 16 to 64 bits wide depending on the platform

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Mostly it depends on the platform you are using  It depends from compiler to compiler Nowadays in most of compilers int is of 4 bytes  If you want to check what your compiler is using you can use sizeof int    main         printf   d  sizeof int        printf   d  sizeof short        printf   d  sizeof long        The only thing c compiler promise is that size of short must be equal or less than int and size of long must be equal or more than int So if size of int is 4  then size of short may be 2 or 4 but not larger than that Same is true for long and int  It also says that size of short and long can not be same

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I know it s equal to sizeof int   The size of an int is really compiler dependent  Back in the day  when processors were 16 bit  an int was 2 bytes  Nowadays  it s most often 4 bytes on a 32-bit as well as 64-bit systems    Still  using sizeof int  is the best way to get the size of an integer for the specific system the program is executed on   EDIT  Fixed wrong statement that int is 8 bytes on most 64-bit systems  For example  it is 4 bytes on 64-bit GCC

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This is a good source for answering this question   But this question is a kind of a always truth answere  Yes  Both    It depends on your architecture  If you re going to work on a 16-bit machine or less  it can t be 4 byte   32 bit   If you re working on a 32-bit or better machine  its length is 32-bit    To figure out  get you program ready to output something readable and use the  sizeof  function  That returns the size in bytes of your declared datatype  But be carfull using this with arrays    If you re declaring int t 12   it will return 12 4 byte  To get the length of this array  just use sizeof t  sizeof t 0     If you are going to build up a function  that should calculate the size of a send array  remember that if  typedef int array 12   int function array t       int size of t   sizeof t  sizeof t 0        return size of t    void main        array t    1 1 1      remember  t   1 1 1 0     0      int a   function t        remember  sending t is just a pointer and equal to int  t    print a        output will be 1  since t will be interpreted as an int itselve       So this won t even return something different  If you define an array and try to get the length afterwards  use sizeof  If you send an array to a function  remember the send value is just a pointer on the first element  But in case one  you always knows  what size your array has  Case two can be figured out by defining two functions and miss some performance  Define function array t  and define function2 array t  int size of t   Call  function t   measure the length by some copy-work and send the result to function2  where you can do whatever you want on variable array-sizes

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include  lt stdio h gt   int main void        printf  size of int   d    int sizeof int        return 0      This returns 4  but it s probably machine dependant

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Is the size of C    int    2 bytes or 4 bytes    The answer is  yes     no     maybe     maybe not    The C programming language specifies the following  the smallest addressable unit  known by char and also called  byte   is exactly CHAR BIT bits wide  where CHAR BIT is at least 8   So  one byte in C is not necessarily an octet  i e  8 bits  In the past one of the first platforms to run C code  and Unix  had 4-byte int - but in total int had 36 bits  because CHAR BIT was 9   int is supposed to be the natural integer size for the platform that has range of at least -32767     32767  You can get the size of int in the platform bytes with sizeof int   when you multiply this value by CHAR BIT you will know how wide it is in bits     While 36-bit machines are mostly dead  there are still platforms with non-8-bit bytes  Just yesterday there was a question about a Texas Instruments MCU with 16-bit bytes  that has a C99  C11-compliant compiler   On TMS320C28x it seems that char  short and int are all 16 bits wide  and hence one byte  long int is 2 bytes and long long int is 4 bytes  The beauty of C is that one can still write an efficient program for a platform like this  and even do it in a portable manner

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There s no specific answer  It depends on the platform  It is implementation-defined  It can be 2  4 or something else   The idea behind int was that it was supposed to match the natural  word  size on the given platform  16 bit on 16-bit platforms  32 bit on 32-bit platforms  64 bit on 64-bit platforms  you get the idea  However  for backward compatibility purposes some compilers prefer to stick to 32-bit int even on 64-bit platforms   The time of 2-byte int is long gone though  16-bit platforms   unless you are using some embedded platform with 16-bit word size  Your textbooks are probably very old

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Does an Integer variable in C occupy 2 bytes or 4 bytes    That depends on the platform you re using  as well as how your compiler is configured  The only authoritative answer is to use the sizeof operator to see how big an integer is in your specific situation        What are the factors that it depends on    Range might be best considered  rather than size  Both will vary in practice  though it s much more fool-proof to choose variable types by range than size as we shall see  It s also important to note that the standard encourages us to consider choosing our integer types based on range rather than size  but for now let s ignore the standard practice  and let our curiosity explore sizeof  bytes and CHAR BIT  and integer representation    let s burrow down the rabbit hole and see it for ourselves       sizeof  bytes and CHAR BIT  The following statement  taken from the C standard  linked to above   describes this in words that I don t think can be improved upon      The sizeof operator yields the size  in bytes  of its operand  which may be an expression or the parenthesized name of a type  The size is determined from the type of the operand    Assuming a clear understanding will lead us to a discussion about bytes  It s commonly assumed that a byte is eight bits  when in fact CHAR BIT tells you how many bits are in a byte  That s just another one of those nuances which isn t considered when talking about the common two  or four  byte integers   Let s wrap things up so far    sizeof    size in bytes  and CHAR BIT    number of bits in byte   Thus  Depending on your system  sizeof  unsigned int  could be any value greater than zero  not just 2 or 4   as if CHAR BIT is 16  then a single  sixteen-bit  byte has enough bits in it to represent the sixteen bit integer described by the standards  quoted below   That s not necessarily useful information  is it  Let s delve deeper       Integer representation  The C standard specifies the minimum precision range for all standard integer types  and CHAR BIT  too  fwiw  here  From this  we can derive a minimum for how many bits are required to store the value  but we may as well just choose our variables based on ranges  Nonetheless  a huge part of the detail required for this answer resides here  For example  the following that the standard unsigned int requires  at least  sixteen bits of storage    UINT MAX                                65535    2  6 - 1    Thus we can see that unsigned int require  at least  16 bits  which is where you get the two bytes  assuming CHAR BIT is 8     and later when that limit increased to 2     - 1  people were stating 4 bytes instead  This explains the phenomena you ve observed      Most of the textbooks say integer variables occupy 2 bytes  But when I run a program printing the successive addresses of an array of integers it shows the difference of 4    You re using an ancient textbook and compiler which is teaching you non-portable C  the author who wrote your textbook might not even be aware of CHAR BIT  You should upgrade your textbook  and compiler   and strive to remember that I T  is an ever-evolving field that you need to stay ahead of to compete    Enough about that  though  let s see what other non-portable secrets those underlying integer bytes store     Value bits are what the common misconceptions appear to be counting  The above example uses an unsigned integer type which typically contains only value bits  so it s easy to miss the devil in the detail   Sign bits    In the above example I quoted UINT MAX as being the upper limit for unsigned int because it s a trivial example to extract the value 16 from the comment  For signed types  in order to distinguish between positive and negative values  that s the sign   we need to also include the sign bit    INT MIN                                -32768    - 2  5  INT MAX                                 32767    2  5 - 1    Padding bits    While it s not common to encounter computers that have padding bits in integers  the C standard allows that to happen  some machines  i e  this one  implement larger integer types by combining two smaller  signed  integer values together    and when you combine signed integers  you get a wasted sign bit  That wasted bit is considered padding in C  Other examples of padding bits might include parity bits and trap bits     As you can see  the standard seems to encourage considering ranges like INT MIN  INT MAX and other minimum maximum values from the standard when choosing integer types  and discourages relying upon sizes as there are other subtle factors likely to be forgotten such as CHAR BIT and padding bits which might affect the value of sizeof  int   i e  the common misconceptions of two-byte and four-byte integers neglects these details

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C99 N1256 standard draft http   www open-std org JTC1 SC22 WG14 www docs n1256 pdf The size of int and all other integer types are implementation defined  C99 only specifies   minimum size guarantees relative sizes between the types  5 2 4 2 1  quot Sizes of integer types  lt limits h gt  quot  gives the minimum sizes   1       Their implementation-defined values shall be equal or greater in magnitude  absolute value  to those shown        UCHAR MAX 255    2 8 - 1 USHRT MAX 65535    2 16 - 1 UINT MAX 65535    2 16 - 1 ULONG MAX 4294967295    2 32 - 1 ULLONG MAX 18446744073709551615    2 64 - 1   6 2 5  quot Types quot  then says   8 For any two integer types with the same signedness and different integer conversion rank  see 6 3 1 1   the range of values of the type with smaller integer conversion rank is a subrange of the values of the other type   and 6 3 1 1  quot Boolean  characters  and integers quot  determines the relative conversion ranks   1 Every integer type has an integer conversion rank defined as follows   The rank of long long int shall be greater than the rank of long int  which shall be greater than the rank of int  which shall be greater than the rank of short int  which shall be greater than the rank of signed char  The rank of any unsigned integer type shall equal the rank of the corresponding signed integer type  if any  For all integer types T1  T2  and T3  if T1 has greater rank than T2 and T2 has greater rank than T3  then T1 has greater rank than T3

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This depends on implementation  but usually on x86 and other popular architectures like ARM ints take 4 bytes  You can always check at compile time using sizeof int  or whatever other type you want to check   If you want to make sure you use a type of a specific size  use the types in  lt stdint h gt

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Is the size of C    int    2 bytes or 4 bytes  Does an Integer variable in C occupy 2 bytes or 4 bytes   C allows  quot bytes quot  to be something other than 8 bits per  quot byte quot     CHAR BIT number of bits for smallest object that is not a bit-field  byte  C11dr   5 2 4 2 1 1   A value of something than 8 is increasingly uncommon   For maximum portability  use CHAR BIT rather than 8   The size of an int in bits  in C is sizeof int    CHAR BIT   include  lt limits h gt  printf  quot  int  Bit size  zu n quot   sizeof int    CHAR BIT      What are the factors that it depends on   The int bit size is commonly 32 or 16 bits   C specified minimum ranges    minimum value for an object of type int INT MIN -32767 maximum value for an object of type int INT MAX  32767 C11dr   5 2 4 2 1 1   The minimum range for int forces the bit size to be at least 16 - even if the processor was  quot 8-bit quot    A size like 64 bits is seen in specialized processors  Other values like 18  24  36  etc  have occurred on historic platforms or are at least theoretically possible   Modern coding rarely worries about non-power-of-2 int bit sizes  The computer s processor and architecture drive the int bit size selection  Yet even with 64-bit processors  the compiler s int size may be 32-bit for compatibility reasons as large code bases depend on int being 32-bit  or 32 16

[c] Is the size of C "int" 2 bytes or 4 bytes?

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