Unexpected behavior in parsing TXT file

[stebif68]

I am reading data using readr. Data is txt file where each column is separate by one (or more) columns of space.
Data has 1000 rows. If I read 996 rows, the first col is an integer. If I read 997 rows, the same first col is character. I guess there is some "special" character but I cannot figure out what's going on

DAT44M100.txt

DatiMorf44xxx <- read_table(file.path(dir,'DAT44M.txt'),col_names = c('id','OpDim',
'YearSeason',
'HerdYear',
'age','age2',
'v1','v2',
'v3','v4',
'v5','v6',
'v7','v8'),
n_max=996)
cols(
id = col_integer(),
OpDim = col_integer(),
YearSeason = col_integer(),
HerdYear = col_integer(),
age = col_integer(),
age2 = col_integer(),
v1 = col_integer(),
v2 = col_integer(),
v3 = col_integer(),
v4 = col_integer(),
v5 = col_integer(),
v6 = col_integer(),
v7 = col_integer(),
v8 = col_integer()
)

DatiMorf44xxx <- read_table(file.path(dir,'DAT44M.txt'),col_names = c('id','OpDim',
'YearSeason',
'HerdYear',
'age','age2',
'v1','v2',
'v3','v4',
'v5','v6',
'v7','v8'),
n_max=997)

cols(
id = col_character(),
OpDim = col_integer(),
YearSeason = col_integer(),
HerdYear = col_integer(),
age = col_integer(),
age2 = col_integer(),
v1 = col_integer(),
v2 = col_integer(),
v3 = col_integer(),
v4 = col_integer(),
v5 = col_integer(),
v6 = col_integer(),
v7 = col_integer(),
v8 = col_integer()
)

[hadley]

Duplicate of #518