Representing single characters
To specify a single character, use char. Typically, the signed char and unsigned char types are not used for single characters but to represent small integer values. C was developed in the time before Unicode and UTF-8. The character set they decided to use was ASCII. All of the necessary characters for printing control, device control, and printable characters and punctuation could be represented in 7 bits.
One reason ASCII was chosen was because of its somewhat logical ordering of uppercase and lowercase letters. An uppercase A and lowercase a are different by only 1 bit. This makes it relatively easy to convert from uppercase into lowercase and vice versa. There is an ASCII table provided for your reference in the Appendix; we also develop a program to print a complete ASCII table in Chapter 15, Working with Strings.
To summarize ASCII's organization, please refer to the following table:
As Unicode, and later...
