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Function std.algorithm.searching.startsWith
Checks whether the given input range starts with (one of) the given needle(s).
Prototypes
uint startsWith(alias pred, Range, Needles...)( Range doesThisStart, Needles withOneOfThese ) if (isInputRange!Range && Needles.length > 1 && is(typeof(.startsWith!pred(doesThisStart, withOneOfThese[0])) : bool) && is(typeof(.startsWith!pred(doesThisStart, withOneOfThese[1..__dollar])) : uint)); bool startsWith(alias pred, R1, R2)( R1 doesThisStart, R2 withThis ) if (isInputRange!R1 && isInputRange!R2 && is(typeof(binaryFun!pred(doesThisStart.front, withThis.front)) : bool)); bool startsWith(alias pred, R, E)( R doesThisStart, E withThis ) if (isInputRange!R && is(typeof(binaryFun!pred(doesThisStart.front, withThis)) : bool));
Parameters
| Name | Description |
|---|---|
| pred | Predicate to use in comparing the elements of the haystack and the needle(s). |
| doesThisStart | The input range to check. |
| withOneOfThese | The needles against which the range is to be checked, which may be individual elements or input ranges of elements. |
| withThis | The single needle to check, which may be either a single element or an input range of elements. |
Returns
0 if the needle(s) do not occur at the beginning of the given range;
otherwise the position of the matching needle, that is, 1 if the range starts
with withOneOfThese[0]withOneOfThese[1]
In the case where doesThisStartwithOneOfThese"a" and 'a'), then
the left-most of them in the argument
list matches).
Example
assert(startsWith("abc", ""));
assert(startsWith("abc", "a"));
assert(!startsWith("abc", "b"));
assert(startsWith("abc", 'a', "b") == 1);
assert(startsWith("abc", "b", "a") == 2);
assert(startsWith("abc", "a", "a") == 1);
assert(startsWith("abc", "ab", "a") == 2);
assert(startsWith("abc", "x", "a", "b") == 2);
assert(startsWith("abc", "x", "aa", "ab") == 3);
assert(startsWith("abc", "x", "aaa", "sab") == 0);
assert(startsWith("abc", "x", "aaa", "a", "sab") == 3);
alias C = Tuple!(int, "x", int, "y");
assert(startsWith!"a.x == b"([ C(1,1), C(1,2), C(2,2) ], [1, 1]));
assert(startsWith!"a.x == b"([ C(1,1), C(2,1), C(2,2) ], [1, 1], [1, 2], [1, 3]) == 2);