count item sequence &key from-end start end key test test-not => n
count-if predicate sequence &key from-end start end key => n
count-if-not predicate sequence &key from-end start end key => n
Arguments and Values:
sequence---a proper sequence.
predicate---a designator for a function of one argument that returns a generalized boolean.
from-end---a generalized boolean. The default is false.
test---a designator for a function of two arguments that returns a generalized boolean.
test-not---a designator for a function of two arguments that returns a generalized boolean.
start, end---bounding index designators of sequence. The defaults for start and end are 0 and nil, respectively.
key---a designator for a function of one argument, or nil.
n---a non-negative integer less than or equal to the length of sequence.
count, count-if, and count-if-not count and return the number of elements in the sequence bounded by start and end that satisfy the test.
The from-end has no direct effect on the result. However, if from-end is true, the elements of sequence will be supplied as arguments to the test, test-not, and key in reverse order, which may change the side-effects, if any, of those functions.
(count #\a "how many A's are there in here?") => 2 (count-if-not #'oddp '((1) (2) (3) (4)) :key #'car) => 2 (count-if #'upper-case-p "The Crying of Lot 49" :start 4) => 2
Side Effects: None.
Affected By: None.
Should be prepared to signal an error of type type-error if sequence is not a proper sequence.
Section 17.2 (Rules about Test Functions), Section 3.6 (Traversal Rules and Side Effects)
The :test-not argument is deprecated.
The function count-if-not is deprecated.