Arrays

Storing many values at once

• An array 数组 is an ordered collection of items of the same type, under one name, reached by an index 索引.
• It's the workhorse for storing lists and tables.
• Loops let you process every element 元素.

1-D arrays

DECLARE Names : ARRAY[1:5] OF STRING
Names[3] ← "Cara"

FOR i ← 1 TO 5
    OUTPUT Names[i]
NEXT i

• An element is one item; the bounds 边界 are the lowest and highest valid indices.
• A FOR loop visits every element in turn.

A 1-D array (a list) with indices and bounds

2-D arrays

DECLARE Grid : ARRAY[1:3, 1:4] OF INTEGER
Grid[2, 3] ← 99      // row 2, column 3

• The first index is the row, the second the column; use nested loops 嵌套循环 to visit every cell.
• Use 1-D for a single sequence, 2-D for a grid (rows × columns).

A 2-D array is a grid, indexed by [row, column].

Common operations

• Linear search 线性查找 checks each element until found:

FOR i ← 1 TO n
    IF A[i] = Target THEN OUTPUT "Found at ", i
NEXT i

• For a sum, count, max or min, set a running variable then sweep through (e.g. Max ← A[1], then compare each element).
• A 2D array is a table with row and column indices, between a lower bound and an upper bound; a bubble sort orders an array by swapping adjacent pairs.

You've got it