How to specify 64 bit integers in c

Question

I m trying to use 64 bit integers in C  but am getting mixed signals as to whether it should be possible   When I execute the printf   printf  Size of long int  d nSize of long long int  d n n   int sizeof long int    int sizeof long long int      The response I get is   Size of long int 4 Size of long long int 8  This makes me feel that a long long int has 8 bytes   64 bits   However  when I try to declare the following variables   long long int a2   0x00004444  long long int b2   0x000044440  long long int c2   0x0000444400  long long int d2   0x00004444000  long long int e2   0x000044440000  long long int f2   0x0000444400004  long long int g2   0x00004444000044  long long int h2   0x000044440000444  long long int i2   0x0000444400004444    The last 4 variables  f2 g2 h2 i2  give me the error message     warning  integer constant is too large for    long    type   I get the same result when I replace  long long int  with  int64 t   I assume  int64 t  was recognized  since it didn t generate any error messages of its own   So  it appears my 8 byte long long int is really a 6 byte long long int  and I don t understand what I m missing here  If it s any help  here is the information on my gcc compiler   me ubuntu    gcc -v   Using built-in specs    Target  i686-linux-gnu   Configured with     src configure -v    --with-pkgversion  Ubuntu Linaro 4 4 4-14ubuntu5    --with-bugurl file    usr share doc gcc-4 4 README Bugs    --enable-languages c c   fortran objc obj-c     --prefix  usr    --program-suffix -4 4    --enable-shared    --enable-multiarch    --enable-linker-build-id    --with-system-zlib    --libexecdir  usr lib    --without-included-gettext    --enable-threads posix    --with-gxx-include-dir  usr include c   4 4    --libdir  usr lib    --enable-nls    --with-sysroot   -   -enable-clocale gnu    --enable-libstdcxx-debug    --enable-objc-gc    --enable-targets all  --disable-werror    --with-arch-32 i686    --with-tune generic    --enable-checking release    --build i686-linux-gnu    --host i686-linux-gnu    --target i686-linux-gnu   Thread model  posix   gcc version 4 4 5  Ubuntu Linaro 4 4 4-14ubuntu5       If anyone knows how  or if  64 bit integers are accessible to me  I d really appreciate any help  Thanks

User · Answer

Use int64 t  that portable C99 code   int64 t var   0x0000444400004444LL    For printing    define   STDC FORMAT MACROS  include  lt inttypes h gt   printf  blabla    PRIi64   blabla n   var

User · Answer

Try an LL suffix on the number  the compiler may be casting it to an intermediate type as part of the parse  See http   gcc gnu org onlinedocs gcc Long-Long html  long long int i2   0x0000444400004444LL   Additionally  the the compiler is discarding the leading zeros  so 0x000044440000 is becoming 0x44440000  which is a perfectly acceptable 32-bit integer  which is why you aren t seeing any warnings prior to f2

User · Answer

How to specify 64 bit integers in c   Going against the usual good idea to appending LL   Appending LL to a integer constant will insure the type is at least as wide as long long   If the integer constant is octal or hex  the constant will become unsigned long long if needed   If ones does not care to specify too wide a type  then LL is OK   else  read on   long long may be wider than 64-bit   Today  it is rare that long long is not 64-bit  yet C specifies long long to be at least 64-bit   So by using LL  in the future  code may be specifying  say  a 128-bit number     C has Macros for integer constants which in the below case will be type int least64 t   include  lt stdint h gt   include  lt inttypes h gt   int main void      int64 t big   INT64 C 9223372036854775807     printf     PRId64   n   big     uint64 t jenny   INT64 C 0x08675309   lt  lt  32      shift was done on at least 64-bit type    printf  0x   PRIX64   n   jenny       output  9223372036854775807 0x867530900000000

User · Answer

Use stdint h for specific sizes of integer data types  and also use appropriate suffixes for integer literal constants  e g     include  lt stdint h gt   int64 t i2   0x0000444400004444LL

User · Answer

Append ll suffix to hex digits for 64-bit  long long int       or ull suffix for unsigned 64-bit  unsigned long long

[c] How to specify 64 bit integers in c

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