| Sequences in Nim are a list of values, but unlike arrays, sequence's length can change at runtime. | |
| Declaring an empty sequence only requires defining the value type. |
var seq1: seq[int]
echo seq1
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To create a non-empty sequence, use the newSeq proc.
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var seq2 = newSeq[bool](5)
seq2[2] = true
echo seq2
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An array can be converted to a sequence by using the @ operator.
This allows initializing the sequence with values the same way as with arrays.
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var seq3 = @['o', 'p', 'r']
echo seq3
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add, insert and delete procs can be used to modify the sequence.
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seq3.add('s')
seq3.insert('q', 2)
seq3.delete(0)
echo seq3
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Sequences can be concatinated with concat proc from sequtils module.
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import sequtils
echo concat(@[1, 2], @[3, 4], @[5, 6])
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| Sequence can be sliced out of an array by addressing an array with a slice. |
var arr1 = ['a', 'b', 'c', 'd', 'e']
var arr1slice = arr1[0..2]
echo arr1slice # is of seq[char] type
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Backwards index operator can be used in a slice to address the array from
the high bound. ^1 is equivalent to arr1.len-1.
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echo arr1[2..^1], " <=> " , arr1[2..arr1.len-1]
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len, low and high procs work with sequences just like with arrays.
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echo "len: ", seq3.len
echo "low: ", seq3.low
echo "high: ", seq3.high
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| Note however, that sequence's index range always starts with 0. |
var arr2: array[10..15, int]
var arr2seq: seq[int] = @arr2
echo "arr2seq range bounds are ",
arr2seq.low, " and ", arr2seq.high
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| Multiple dimension sequences can be declared as well. |
var seq2d: seq[seq[int]]
echo seq2d
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Sequences' values can be iterated with for just like with arrays.
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for index, value in arr2seq:
echo index, "=", value
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$ nim c -r sequences.nim @[] @[false, false, true, false, false] @['o', 'p', 'r'] @['p', 'q', 'r', 's'] @[1, 2, 3, 4, 5, 6] @['a', 'b', 'c'] @['c', 'd', 'e'] <=> @['c', 'd', 'e'] len: 4 low: 0 high: 3 arr2seq range bounds are 0 and 5 @[] 0=0 1=0 2=0 3=0 4=0 5=0 |
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