What is char octal escape sequence?
A character literal can be expressed as an octal escape sequence in the form '\nnn'.
n is an octal digit (0-7). The range for the octal escape sequence is '\000' to '\377'.
The octal number 377 is the same as the decimal number 255.
Using octal escape sequence, you can represent characters whose Unicode code range from 0 to 255 decimal integers.