This function returns
tif the arguments represent the same character,
nilotherwise. This function ignores differences in case if
nil.(char-equal ?x ?x) ⇒ t (let ((case-fold-search nil)) (char-equal ?x ?X)) ⇒ nil
This function returns
tif the characters of the two strings match exactly. Symbols are also allowed as arguments, in which case the symbol names are used. Case is always significant, regardless of
This function is equivalent to
equalfor comparing two strings (see Equality Predicates). In particular, the text properties of the two strings are ignored. But if either argument is not a string or symbol, an error is signaled.(string= "abc" "abc") ⇒ t (string= "abc" "ABC") ⇒ nil (string= "ab" "ABC") ⇒ nil
For technical reasons, a unibyte and a multibyte string are
equalif and only if they contain the same sequence of character codes and all these codes are either in the range 0 through 127 (ASCII) or 160 through 255 (
eight-bit-graphic). However, when a unibyte string is converted to a multibyte string, all characters with codes in the range 160 through 255 are converted to characters with higher codes, whereas ASCII characters remain unchanged. Thus, a unibyte string and its conversion to multibyte are only
equalif the string is all ASCII. Character codes 160 through 255 are not entirely proper in multibyte text, even though they can occur. As a consequence, the situation where a unibyte and a multibyte string are
equalwithout both being all ASCII is a technical oddity that very few Emacs Lisp programmers ever get confronted with. See Text Representations.
This function compares two strings a character at a time. It scans both the strings at the same time to find the first pair of corresponding characters that do not match. If the lesser character of these two is the character from string1, then string1 is less, and this function returns
t. If the lesser character is the one from string2, then string1 is greater, and this function returns
nil. If the two strings match entirely, the value is
Pairs of characters are compared according to their character codes. Keep in mind that lower case letters have higher numeric values in the ASCII character set than their upper case counterparts; digits and many punctuation characters have a lower numeric value than upper case letters. An ASCII character is less than any non-ASCII character; a unibyte non-ASCII character is always less than any multibyte non-ASCII character (see Text Representations).(string< "abc" "abd") ⇒ t (string< "abd" "abc") ⇒ nil (string< "123" "abc") ⇒ t
When the strings have different lengths, and they match up to the length of string1, then the result is
t. If they match up to the length of string2, the result is
nil. A string of no characters is less than any other string.(string< "" "abc") ⇒ t (string< "ab" "abc") ⇒ t (string< "abc" "") ⇒ nil (string< "abc" "ab") ⇒ nil (string< "" "") ⇒ nil
Symbols are also allowed as arguments, in which case their print names are used.
This function returns non-
nilif string1 is a prefix of string2; i.e., if string2 starts with string1. If the optional argument ignore-case is non-
nil, the comparison ignores case differences.
This function compares a specified part of string1 with a specified part of string2. The specified part of string1 runs from index start1 (inclusive) up to index end1 (exclusive);
nilfor start1 means the start of the string, while
nilfor end1 means the length of the string. Likewise, the specified part of string2 runs from index start2 up to index end2.
The strings are compared by the numeric values of their characters. For instance, str1 is considered “smaller than” str2 if its first differing character has a smaller numeric value. If ignore-case is non-
nil, characters are converted to lower-case before comparing them. Unibyte strings are converted to multibyte for comparison (see Text Representations), so that a unibyte string and its conversion to multibyte are always regarded as equal.
If the specified portions of the two strings match, the value is
t. Otherwise, the value is an integer which indicates how many leading characters agree, and which string is less. Its absolute value is one plus the number of characters that agree at the beginning of the two strings. The sign is negative if string1 (or its specified portion) is less.
This function works like
assoc, except that key must be a string or symbol, and comparison is done using
compare-strings. Symbols are converted to strings before testing. If case-fold is non-
nil, it ignores case differences. Unlike
assoc, this function can also match elements of the alist that are strings or symbols rather than conses. In particular, alist can be a list of strings or symbols rather than an actual alist. See Association Lists.
See also the function
Comparing Text, for a way to compare text in buffers. The
string-match, which matches a regular expression
against a string, can be used for a kind of string comparison; see