One-dimensional arrays
The 1D array: size, indices from 0 to n − 1, access and modification, traversal by index or by element, out-of-bounds access, shifting to insert or delete, and copying.
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Array: what is it?
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A sequence of cells of the same type stored side by side in memory, each identified by its position.
Reading or writing a cell by its number always takes the same time:
t[0]andt[999]are equally fast.What does this program print?
```python
t = [4, 7, 1, 9]
for i in range(len(t) - 1):
t[i] = t[i + 1]
print(t)`[7, 1, 9, 9][7, 1, 9, 4][4, 4, 7, 1][7, 1, 9]
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[7, 1, 9, 9]Each cell receives the value of its right-hand neighbour; the last one is never modified and keeps 9. The array keeps its size: nothing is removed, one value is just duplicated.
An array of n cells has its indices from … to ….
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An array of n cells has its indices from 0 to n - 1.
With 12 cells, the last one has index 11: index n does not exist, and it is the most common off-by-one error.
Index: what is it?
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The number that identifies a cell of an array; the first cell has number 0.
It is the distance from the first cell, hence the 0. With n cells, the indices run from 0 to n − 1: the last cell is
t[len(t) - 1].