字符和字符串（Characters and strings）.doc

字符和字符串（Characters and strings） The use of characters and string types (a) character type A character, literal, or character variable consisting of a character, defined by a literal constant: Const Character constant = character; Character variable definition: Var Character variable: char; The character type is an ordered type, and the size of the character is ordered in accordance with the size of its ASC II code. Functions succ, PRED, and ord apply to character types, for example: Successor function: succ (a) = B Forward continuation function: PRED (B) = A Serial number function: ord (A) =65 [example 1] print each letter in alphabetical order and reverse order at any other letter: A, C, e, G, I, K, m, O, Q, s,, u, W, y Z, x, R, V, t, P, N, l, J, h,, F, D, B Procedures are as follows: Program ex8_1; Var letter:char; Begin For letter:=, a, to, Z, do If (ord (letter) -ord (a)) mod, 2=0, then, write (letter:3); Writeln; For letter:=, Z, downto, a, do If (ord (letter) -ord (Z)) mod 2, =0, then, write (letter:3); Writeln; End. Analysis: in the program, we take advantage of the characteristic that the character type is a sequential type, which directly takes the character type variable as the loop variable, so that the program is handled more intuitively. (two) string type A string is a sequence of characters, a string, and a string type definition: Type string type identifier =string[n]; Var String variables: string type identifiers; Where: n is the length of the string must be defined, 0~255 between natural integers, the actual length of storage on the No. zeroth unit, when the program is run by the system automatically provides storage on Unit No. 1~n in character, if written in string[n] string, the default value is 255 n. For example: type Man=string[8]; Line=string; Var Name:man; Screenline:line; Another type of character is defined by merging the variable definitions of type descriptions. For example: VAR Name:STRING[8]; Screenline:STRING; In Turbo Pascal, charact