string= compares two strings and is true if they are the same (corresponding characters are identical) but is false if they are not. The function equal calls string= if applied to two strings.

The keyword arguments :start1 and :start2 are the places in the strings to start the comparison. The arguments :end1 and :end2 are the places in the strings to stop comparing; comparison stops just before the position specified by a limit. The “start” arguments default to zero (beginning of string), and the “end” arguments (if either omitted or nil) default to the lengths of the strings (end of string), so that by default the entirety of each string is examined. These arguments are provided so that substrings can be compared efficiently.

string= is necessarily false if the (sub)strings being compared are of unequal length; that is, if

is true, then string= is false.

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. For example:

These functions compare the two string arguments lexicographically, and the result is nil unless string1 is respectively less than, greater than, less than or equal to, greater than or equal to, or not equal to string2. If the condition is satisfied, however, then the result is the index within the strings of the first character position at which the strings fail to match; put another way, the result is the length of the longest common prefix of the strings.

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 the function char<, or if string a is a proper prefix of string b (of shorter length and matching in all the characters of a).

The keyword arguments :start1 and :start2 are the places in the strings to start the comparison. The keyword arguments :end1 and :end2 are the places in the strings to stop comparing; comparison stops just before the position specified by a limit. The “start” arguments default to zero (beginning of string), and the “end” arguments (if either omitted or nil) default to the lengths of the strings (end of string), so that by default the entirety of each string is examined. These arguments are provided so that substrings can be compared efficiently. The index returned in case of a mismatch is an index into string1.

These are exactly like string<, string>, string<=, 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.