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Strings

Character Codes

Character codes are mappings between numbers and symbols which make up a particular alphabet.

The American Standard Code for Information Interchange (ASCII) is a single-byte character code where 2^7 = 128 characters are specified.

Symbol assignments were not done at random. Several interesting properties of the design make programming tasks easier:

• All non-printable characters have either the first three bits as zero or all seven lowest bits as one. This makes it easy to eliminate them before displaying junk.
• Both the upper and lower case letters and the numerical digits appear sequentially
• We can get the numeric order of a letter by subtracting the first letter
• We can convert a character from uppercase to lowercase by Letter - "A" + "a"