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Comparison of Characters

procedure: char=? char1 char2

procedure: char<? char1 char2

procedure: char>? char1 char2

procedure: char<=? char1 char2

procedure: char>=? char1 char2

procedure: char-ci=? char1 char2

procedure: char-ci<? char1 char2

procedure: char-ci>? char1 char2

procedure: char-ci<=? char1 char2

procedure: char-ci>=? char1 char2

Returns #t if the specified characters are have the appropriate order relationship to one another; otherwise returns #f. The -ci procedures don't distinguish uppercase and lowercase letters.

Character ordering follows these rules:

• The digits are in order; for example, (char<? #\0 #\9) returns #t.

• The uppercase characters are in order; for example, (char<? #\A #\B) returns #t.

• The lowercase characters are in order; for example, (char<? #\a #\b) returns #t.

In addition, MIT Scheme orders those characters that satisfy char-standard? the same way that ASCII does. Specifically, all the digits precede all the uppercase letters, and all the upper-case letters precede all the lowercase letters.

Characters are ordered by first comparing their bucky bits part and then their code part. In particular, characters without bucky bits come before characters with bucky bits.

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