How to print a int64 t type in C

Question

C99 standard has integer types with bytes size like int64 t  I am using the following code    include  lt stdio h gt   include  lt stdint h gt  int64 t my int   999999999999999999  printf  This is my int   I64d n   my int     and I get this compiler warning   warning  format     I64d    expects type    int     but argument 2 has type    int64 t      I tried with   printf  This is my int   lld n   my int      long long decimal   But I get the same warning  I am using this compiler     dev c  cc -v Using built-in specs  Target  i686-apple-darwin10 Configured with   var tmp gcc gcc-5664 89 src configure --disable-checking --enable-werror --prefix  usr --mandir  share man --enable-languages c objc c   obj-c   --program-transform-name    cg    -    s   -4 2  --with-slibdir  usr lib --build i686-apple-darwin10 --program-prefix i686-apple-darwin10- --host x86 64-apple-darwin10 --target i686-apple-darwin10 --with-gxx-include-dir  include c   4 2 1 Thread model  posix gcc version 4 2 1  Apple Inc  build 5664    Which format should I use to print my int variable without having a warning

User · Accepted Answer

For int64 t type    include  lt inttypes h gt  int64 t t  printf     PRId64   n   t     for uint64 t type    include  lt inttypes h gt  uint64 t t  printf     PRIu64   n   t     you can also use PRIx64 to print in hexadecimal   cppreference com has a full listing of available macros for all types including intptr t  PRIxPTR    There are separate macros for scanf  like SCNd64     A typical definition of PRIu16 would be  hu   so implicit string-constant concatenation happens at compile time   For your code to be fully portable  you must use PRId32 and so on for printing int32 t  and   d  or similar for printing int

User · Answer

In windows environment  use   I64d   in Linux  use   lld

User · Answer

With C99 the  j length modifier can also be used with the printf family of functions to print values of type int64 t and uint64 t    include  lt stdio h gt   include  lt stdint h gt   int main int argc  char  argv          int64 t  a   1LL  lt  lt  63      uint64 t b   1ULL  lt  lt  63       printf  a  jd  0x jx  n   a  a       printf  b  ju  0x jx  n   b  b        return 0      Compiling this code with gcc -Wall -pedantic -std c99 produces no warnings  and the program prints the expected output   a -9223372036854775808  0x8000000000000000  b 9223372036854775808  0x8000000000000000    This is according to printf 3  on my Linux system  the man page specifically says that j is used to indicate a conversion to an intmax t or uintmax t  in my stdint h  both int64 t and intmax t are typedef d in exactly the same way  and similarly for uint64 t   I m not sure if this is perfectly portable to other systems

User · Answer

VC6 0  386  amp  better         int64 my qw var   0x1234567890abcdef         int32 v dw h        int32 v dw l         asm                       mov eax  dword ptr my qw var   4      dwh             mov  dword ptr v dw h  eax              mov eax  dword ptr my qw var      dwl             mov  dword ptr v dw l  eax                      Oops 0 8 format     printf  val   0x 0 8x 0 8x n      int32 v dw h     int32 v dw l     Regards

User · Answer

The C99 way is   include  lt inttypes h gt  int64 t my int   999999999999999999  printf     PRId64   n   my int     Or you could cast   printf   ld    long my int   printf   lld    long long my int      C89 didn t define  long long     printf   f    double my int     If you re stuck with a C89 implementation  notably Visual Studio  you can perhaps use an open source  lt inttypes h gt   and  lt stdint h gt    http   code google com p msinttypes

User · Answer

Coming from the embedded world  where even uclibc is not always available  and code like  uint64 t myval   0xdeadfacedeadbeef  printf   llx   myval    is printing you crap or not working at all -- i always use a tiny helper  that allows me to dump properly uint64 t hex    include  lt stdlib h gt   include  lt stdio h gt   include  lt stdint h gt   char  ullx uint64 t val        static char buf 34       0     33    0        char  out    amp buf 33       uint64 t hval   val      unsigned int hbase   16       do            out    0123456789abcdef  hval   hbase           --out          hval    hbase        while hval         out--    x    out    0        return out

[c] How to print a int64_t type in C

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