C Pocket Reference

Character Sets

ANSI C defines two character sets. The first is the source character set , which is the set of characters that may be used in a source file. The second is the execution character set , which consists of all the characters that are interpreted during the execution of the program, such as the characters in a string constant.

Each of these character sets contains a basic character set , which includes the following:

• The 52 upper- and lower-case letters of the Latin alphabet:

  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
  a b c d e f g h i j k l m n o p q r s t u v w x y z

• The ten decimal digits (where the value of each character after 0 is one greater than the previous digit):

  0  1  2  3  4  5  6  7  8  9

• The following 29 graphic characters:

  !  "  #  %  &  '  (  )  *  +  ,  -  .  /  :  ;
  <  =  >  ?  [  \  ]  ^  _  {  |  }  ~

• The five whitespace characters:

  space, horizontal tab, vertical tab, newline, form feed

In addition, the basic execution character set contains the following:

• The null character \0, which terminates a character string

• The control characters represented by simple escape sequences , shown in Table 1-1, for controlling output devices such as terminals or printers

Table 1-1. The standard escape sequences

Escape sequence	Action ondisplay device		Escape sequence	Action ondisplay device
\a	Alert (beep)		\'	The character '
\b	Backspace		\"	The character "
\f	Form feed		\?	The character ?
\n	Newline		\\	The character \
\r	Carriage return		\o \oo \ooo(o = octal digit) ...