CLHS: Function STRING=, STRING/=, STRING<...

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Function STRING=, STRING/=, STRING<, STRING>, STRING<=, STRING>=, STRING-EQUAL, STRING-NOT-EQUAL, STRING-LESSP, STRING-GREATERP, STRING-NOT-GREATERP, STRING-NOT-LESSP

Syntax:

string= string1 string2 `&key` start1 end1 start2 end2 => generalized-boolean

string/= string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string< string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string> string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string<= string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string>= string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string-equal string1 string2 `&key` start1 end1 start2 end2 => generalized-boolean

string-not-equal string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string-lessp string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string-greaterp string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string-not-greaterp string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

string-not-lessp string1 string2 `&key` start1 end1 start2 end2 => mismatch-index

Arguments and Values:

string1---a string designator.

string2---a string designator.

start1, end1---bounding index designators of string1. The defaults for start and end are `0` and nil, respectively.

start2, end2---bounding index designators of string2. The defaults for start and end are `0` and nil, respectively.

generalized-boolean---a generalized boolean.

mismatch-index---a bounding index of string1, or nil.

Description:

These functions perform lexicographic comparisons on string1 and string2. string= and string-equal are called equality functions; the others are called inequality functions. The comparison operations these functions perform are restricted to the subsequence of string1 bounded by start1 and end1 and to the subsequence of string2 bounded by start2 and end2.

A string a is equal to a string b if it contains the same number of characters, and the corresponding characters are the same under char= or char-equal, as appropriate.

A string a is less than a string b if in the first position in which they differ the character of a is less than the corresponding character of b according to char< or char-lessp as appropriate, or if string a is a proper prefix of string b (of shorter length and matching in all the characters of a).

The equality functions return a generalized boolean that is true if the strings are equal, or false otherwise.

The inequality functions return a mismatch-index that is true if the strings are not equal, or false otherwise. When the mismatch-index is true, it is an integer representing the first character position at which the two substrings differ, as an offset from the beginning of string1.

The comparison has one of the following results:

string=

  string= is true if the supplied substrings are of the same length and contain the same characters in corresponding positions; otherwise it is false.

string/=

  string/= is true if the supplied substrings are different; otherwise it is false.

string-equal

  string-equal is just like string= except that differences in case are ignored; two characters are considered to be the same if char-equal is true of them.

string<

  string< is true if substring1 is less than substring2; otherwise it is false.

string>

  string> is true if substring1 is greater than substring2; otherwise it is false.

string-lessp, string-greaterp

  string-lessp and string-greaterp are exactly like string< and string>, respectively, except that distinctions between uppercase and lowercase letters are ignored. It is as if char-lessp were used instead of char< for comparing characters.

string<=

  string<= is true if substring1 is less than or equal to substring2; otherwise it is false.

string>=

  string>= is true if substring1 is greater than or equal to substring2; otherwise it is false.

string-not-greaterp, string-not-lessp

  string-not-greaterp and string-not-lessp are exactly like string<= and string>=, respectively, except that distinctions between uppercase and lowercase letters are ignored. It is as if char-lessp were used instead of char< for comparing characters.

Examples:

     (string= "foo" "foo") =>  true
     (string= "foo" "Foo") =>  false
     (string= "foo" "bar") =>  false
     (string= "together" "frog" :start1 1 :end1 3 :start2 2) =>  true
     (string-equal "foo" "Foo") =>  true
     (string= "abcd" "01234abcd9012" :start2 5 :end2 9) =>  true
     (string< "aaaa" "aaab") =>  3
     (string>= "aaaaa" "aaaa") =>  4
     (string-not-greaterp "Abcde" "abcdE") =>  5
     (string-lessp "012AAAA789" "01aaab6" :start1 3 :end1 7
                                          :start2 2 :end2 6) =>  6
     (string-not-equal "AAAA" "aaaA") =>  false

Side Effects: None.

Affected By: None.

Exceptional Situations: None.

See Also:

char=

Notes:

equal calls string= if applied to two strings.

The following X3J13 cleanup issues, not part of the specification, apply to this section:

- RANGE-OF-START-AND-END-PARAMETERS:INTEGER-AND-INTEGER-NIL
- SUBSEQ-OUT-OF-BOUNDS
- STRING-COERCION:MAKE-CONSISTENT

Copyright 1996-2005, LispWorks Ltd. All rights reserved.