[R] Potential bug in readLines when reading empty lines

[Heuvel, E.G. van den (Guido)]

Hi all, 

I encountered some weird behaviour with readLines() recently, and I am wondering if this might be a bug, or, if it is not, how to resolve it. The issue is as follows:

If I have a text file where a line ends with just a carriage return (\r, CR) while the next line is empty and ends in a carriage return / linefeed (\r\n, CR LF), then the empty line is skipped when reading the file with readLines. The following code contains a test case:

---
print(R.version)
# platform       x86_64-w64-mingw32               
# arch           x86_64                           
# os             mingw32                          
# crt            ucrt                             
# system         x86_64, mingw32                  
# status                                          
# major          4                                
# minor          4.0                              
# year           2024                             
# month          04                               
# day            24                               
# svn rev        86474                            
# language       R                                
# version.string R version 4.4.0 (2024-04-24 ucrt)
# nickname       Puppy Cup  

txt_original <- paste0("Line 1\r", "\r\n", "Line 3\r\n")

# Write txt_original as binary to avoid unwanted conversion of end of line markers
writeBin(charToRaw(txt_original), "test.txt")

txt_actual <- readLines("test.txt")
print(txt_actual)
# [1] "Line 1" "Line 3"
 ---

I included the output of this script on my machine in the comments. I would expect txt_actual to be equal to c("Line 1", "", "Line 3"), but the empty line is skipped.

Is this a bug? And if not, how should I read test.txt in such a way that the empty 2nd line is left intact?

Best regards,

Guido van den Heuvel
Statistics Netherlands