[fread] Error message is not displayed when a field ends with percent sign

[etienne-s]

Minimal example, tested on both CRAN and dev versions:

fread("name,id\nfoo,1\nbar%\n")
# Error in fread("name,id\nfoo,1\nbar%\n") : 

[st-pasha]

Could you please provide more details about your system (sessionInfo()). The example that you provided seems to work correctly on my machine:

> fread("name,id\nfoo,1\nbar%\n")
Error in fread("name,id\nfoo,1\nbar%\n") : 
  Line 2 has too few fields when detecting types. Use fill=TRUE to pad with NA. Expecting 2 fields but found 1: <<bar>>

[etienne-s]

sessionInfo()
# R version 3.4.1 (2017-06-30)
# Platform: x86_64-w64-mingw32/x64 (64-bit)
# Running under: Windows 7 x64 (build 7601) Service Pack 1
# 
# Matrix products: default
# 
# locale:
# [1] LC_COLLATE=French_France.1252  LC_CTYPE=French_France.1252    LC_MONETARY=French_France.1252
# [4] LC_NUMERIC=C                   LC_TIME=French_France.1252    
# 
# attached base packages:
# [1] stats     graphics  grDevices utils     datasets  methods   base     
# 
# other attached packages:
# [1] data.table_1.10.5
# 
# loaded via a namespace (and not attached):
# [1] compiler_3.4.1 tools_3.4.1  

If it can help, this is the error I get with a slightly different command:

fread("name,id\nfoo,1\nb%ar\n")
# Error in fread("name,id\nfoo,1\nb%ar\n") : 
#   Line 2 has too few fields when detecting types. Use fill=TRUE to pad with NA. Expecting 2 fields but found 1: <<b0x1.1812000360018p+711r>>

As you can see %a is replaced by 0x1.1812000360018p+711 in the message.

Note: On my Linux system everything works properly.

[st-pasha]

Thanks Etienne, this was helpful.
Seems like this problem appears on Windows / MacOS machines only. We'll try to resolve it asap because there appears to be a potential for a crash, not merely a poor error message.