Pack format 'c' is for signed chars, which means that once you get values above 127, you get a warning.

If you switch to format 'C4' (where C is unsigned char), the warnings will go away:

P:\test>perl -wle "print( $_ ), print pack'c*', $_ for 125..130"
125
}
126
~
127

128
Character in 'c' format wrapped in pack at -e line 1.
Ç
129
Character in 'c' format wrapped in pack at -e line 1.
ü
130
Character in 'c' format wrapped in pack at -e line 1.
é

P:\test>perl -wle "print( $_ ), print pack'C*', $_ for 125..130"
125
}
126
~
127

128
Ç
129
ü
130
é
[download]