c++ - Warning C4267 'argument': conversion from 'size_t' to 'DWORD', possible loss of data -


i migrating code 32bit vs2012 64bit vs2015.

i encountered following function call in program:

crypthashdata(hhash,                  (byte*)auth_encryption_key,                     wcslen(auth_encryption_key) * sizeof(wchar_t),                     0u))

whose declaration in wincrypt.h located in c:\program files (x86)\windows kits\8.0\include\um\wincrypt.h (looks not edited).

the declaration is:

winadvapi bool winapi crypthashdata( _in_                    hcrypthash  hhash, _in_reads_bytes_(dwdatalen)  const byte  *pbdata, _in_                    dword   dwdatalen, _in_                    dword   dwflags );

dword dwflags: problem here 0u unsigned int , function needs dword.

to solve error did:

  • c-style casting (dword)(0u) in function call(tried size_t, unsigned int)
  • static_cast
  • tried creating new variable , casted it

but warning still persists

looks have change in function call

can suggest me how solve issue.

please ask if more details required.

warning image details
later warning image details

you thinking of 0u being problem.
me looks problem should around third parameter, size_t value used feed dword parameter.

as someprogrammerdude has explained, size_t 64bit in new environment, while dword 32bit. explains mismatch on new platform.

on 32bit platform did not warning (i assume), because size_t 32bit there, without risk of loosing information.

you reported casting avoids warning, indicates 0u not problem.
fact warning seems on line 0u caused compiler complaining whole function call , pin pointing end of it, i.e. closing ), happens on same line 0u.
experiment of moving ) separate lines (result visible difference bwetween 2 screenshots) has confirmed this.

note casting avoided warning, not same solving problem.
(you wisely asked safety of casting, recommend in separate question.)


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