octave: X11 DISPLAY environment variable not set
octave: disabling GUI features
warning: implicit conversion from numeric to char
warning: called from
    reverseFile at line 9 column 22

Your reverse.txt:

efiL ocisoH fo yad enO
gnimmiwS
ocisoH rof dnalyensiD
xaler ot yad doog a s'tI
xoB daerB taC gnizamA ehT
ocisoH tuoba stcaF
!yaD yrotciV yppaH
emoh ta srebmucuc worg ylkciuq ot woH
skeehc yffulf s'ocisoH gnigassam rof tseb eht era seldnah elttil esehT�

Your reverse.txt:
efiL ocisoH fo yad enO
gnimmiwS
ocisoH rof dnalyensiD
xaler ot yad doog a s'tI
xoB daerB taC gnizamA ehT
ocisoH tuoba stcaF
!yaD yrotciV yppaH
emoh ta srebmucuc worg ylkciuq ot woH
skeehc yffulf s'ocisoH gnigassam rof tseb eht era seldnah elttil esehT