std.algorithm.searching.count - multiple declarations
Function count
Counts matches of needle in haystack.
size_t count(alias pred, Range, E)
(
Range haystack,
E needle
)
if (isInputRange!Range && !isInfinite!Range && is(typeof(binaryFun!pred(haystack
size_t count(alias pred, R1, R2)
(
R1 haystack,
R2 needle
)
if (isForwardRange!R1 && !isInfinite!R1 && isForwardRange!R2 && is(typeof(binaryFun!pred(haystack
The first overload counts each element e in haystack for
which pred(e, needle) is true. pred defaults to
equality. Performs Ο(haystack) evaluations of pred.
The second overload counts the number of times needle was matched in
haystack. pred compares elements in each range.
Throws an exception if needle is true, as the count
of the empty range in any range would be infinite. Overlapped counts
are *not* considered, for example count("aaa", "aa") is 1, not
2.
Note
Regardless of the overload, count will not accept
infinite ranges for haystack.
Parameters
| Name | Description |
|---|---|
| pred | The predicate to compare elements. |
| haystack | The range to count. |
| needle | The element or sub-range to count in haystack. |
Returns
The number of matches in haystack.
Example
// count elements in range
int[] a = [ 1, 2, 4, 3, 2, 5, 3, 2, 4 ];
writeln(count(a, 2)); // 3
writeln(count!("a > b")(a, 2)); // 5
Example
import stdFunction count
Counts all elements or elements satisfying a predicate in haystack.
size_t count(alias pred, R)
(
R haystack
)
if (isInputRange!R && !isInfinite!R && is(typeof(unaryFun!pred(haystack
size_t count(R)
(
R haystack
)
if (isInputRange!R && !isInfinite!R);
The first overload counts each element e in haystack for which pred(e) is true. Performs Ο(haystack) evaluations of pred.
The second overload counts the number of elements in a range.
If the given range has the length property,
that is returned right away, otherwise
performs Ο(haystack) to walk the range.
Parameters
| Name | Description |
|---|---|
| pred | Optional predicate to find elements. |
| haystack | The range to count. |
Returns
The number of elements in haystack (for which pred returned true).
Example
// count elements in range
int[] a = [ 1, 2, 4, 3, 2, 5, 3, 2, 4 ];
writeln(count(a)); // 9
// count predicate in range
writeln(count!("a > 2")(a)); // 5