Function std.range.padLeft
Extends the length of the input range r
by padding out the start of the
range with the element e
. The element e
must be of a common type with
the element type of the range r
as defined by CommonType
.
If n
is less than the length of of r
, then r
is returned unmodified.
auto padLeft(R, E)
(
R r,
E e,
size_t n
)
if ((isInputRange!R && hasLength!R || isForwardRange!R) && !is(CommonType!(ElementType!R, E) == void));
If r
is a string with Unicode characters in it, padLeft
follows D's rules
about length for strings, which is not the number of characters, or
graphemes, but instead the number of encoding units. If you want to treat each
grapheme as only one encoding unit long, then call
byGrapheme
before calling this function.
If r
has a length, then this is Ο(1
). Otherwise, it's Ο(r
).
Parameters
Name | Description |
---|---|
r | an input range with a length, or a forward range |
e | element to pad the range with |
n | the length to pad to |
Returns
A range containing the elements of the original range with the extra padding
See Also:
leftJustifier
Example
import std .algorithm .comparison : equal;
assert([1, 2, 3, 4] .padLeft(0, 6) .equal([0, 0, 1, 2, 3, 4]));
assert([1, 2, 3, 4] .padLeft(0, 3) .equal([1, 2, 3, 4]));
assert("abc" .padLeft('_', 6) .equal("___abc"));
Authors
Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.