writting null (\000 or ^@) to an external text file without the new warning

Barry Rowlingson · 2008-10-28T19:57:07Z

2008/10/28 Greg Snow : > I have some functions that write an external text file for postprocessing by another program. Some instructions to the other program need to be indicated by null values (\000 or ^@). The function currently uses code like: > > writeChar(rawToChar(as.raw(0)), con) > > where con is a connection to the file. Previous to version 2.8.0 this worked fine. With 2.8.0 it still works, but I get a warning message about "truncating string with embedded nul

Barry Rowlingson

Tue, Oct 28, 2008 12:57 PM

2008/10/28 Greg Snow <Greg.Snow at imail.org>:

The warning happens when you construct the string, so somehow you
have to avoid making the string. How about using writeBin with a
connection opened in binary mode:

 > con=file("test2.raw","wb")
 > writeBin(as.raw(1),con,size=1)
 > writeBin(as.raw(0),con,size=1)
 > writeBin(as.raw(0),con,size=1)
 > writeBin(as.raw(7),con,size=1)
 > close(con)
 >
Save workspace image? [y/n/c]: n

 now lets dump it:

 rowlings at fab008000006:~$ od -x test2.raw
 0000000 0001 0700
 0000004

 Which I think is correct, maybe some fiddling with endianness is needed...

Barry

writting null (\000 or ^@) to an external text file without the new warning

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