$ echo Zúñigä > input.txt
$ cat input.txt
Zúñigä
$ cc -g -Wall -Wextra ascii.c -o ascii
$ ./ascii < input.txt
[Z][[[[[i][g][[[
]$cc -g -Wall -Wextra unicode.c -o unicode
$ ./unicode < input.txt 
[Z][ú][ñ][i][g][ä][
]$ file input.txt
input.txt: UTF-8 Unicode text
$ xxd input.txt 
00000000: 5ac3 bac3 b169 67c3 a40a                 Z....ig...