what is the unsigned datatype

Question

I ve seen this unsigned  typeless  type used a couple of times  but never seen an explanation for it  I suppose there s a corresponding signed type  Here s an example   static unsigned long next   1     RAND MAX assumed to be 32767    int myrand void        next   next   1103515245   12345      return  unsigned  next 65536    32768     void mysrand unsigned seed        next   seed     What I have gathered so far  - on my system  sizeof unsigned    4  hints at a 32-bit unsigned int  - it might be used as a shorthand for casting another type to the unsigned version   signed long int i   -42  printf   u n    unsigned i     Is this ANSI C  or just a compiler extension

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unsigned really is a shorthand for unsigned int  and so defined in standard C

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Historically in C  if you omitted a datatype  int  was assumed  So  unsigned  is a shorthand for  unsigned int   This has been considered bad practice for a long time  but there is still a fair amount of code out there that uses it

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According to C17 6 7 2   2      Each list of type specifiers shall be one of the following multisets  delimited by commas  when there is more than one multiset per item   the type specifiers may occur in any order  possibly intermixed with the other declaration specifiers          void       char       signed char       unsigned char       short  signed short  short int  or signed short int       unsigned short  or unsigned short int       int  signed  or signed int       unsigned  or unsigned int       long  signed long  long int  or signed long int       unsigned long  or unsigned long int       long long  signed long long  long long int  or signed long long int       unsigned long long  or unsigned long long int       float       double       long double        Bool       float  Complex       double  Complex       long double  Complex       atomic type specifier       struct or union specifier       enum specifier       typedef name     So in case of unsigned int we can either write unsigned or unsigned int  or if we are feeling crazy  int unsigned  The latter since the standard is stupid enough to allow     may occur in any order  possibly intermixed   This is a known flaw of the language   Proper C code uses unsigned int

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unsigned means unsigned int   signed means signed int   Using just unsigned is a lazy way of declaring an unsigned int in C   Yes this is ANSI

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in C  unsigned is a shortcut for unsigned int   You have the same for long that is a shortcut for long int  And it is also possible to declare a unsigned long  it will be a unsigned long int    This is in the ANSI standard

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In C and C    unsigned   unsigned int  Integer type  signed     signed int  Integer type    An unsigned integer containing n bits can have a value between 0 and   2 n-1    which is 2 n different values   An unsigned integer is either positive or zero   Signed integers are stored in a computer using 2 s complement

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Bringing my answer from another question   From the C specification  section 6 7 2          unsigned  or unsigned int   Meaning that unsigned  when not specified the type  shall default to  unsigned int  So writing unsigned a is the same as unsigned int a

[c] what is the unsigned datatype?

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