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  ANSI Common Lisp   16 Strings   16.2 Dictionary of Strings

16.2.10 string=, string/=, string<, string>, string<=, string>=, string-equal, string-not-equal, string-lessp, string-greaterp, string-not-greaterp, string-not-lessp Function

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:

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

See Also:
char=

Notes:
equal calls string= if applied to two strings.

Allegro CL Implementation Details:
None.

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