One- and two-dimensional arrays, looping through them, and string handling: length, substrings, character codes and concatenation.
What you will learn
- Read items from 1D and 2D arrays by index
- Loop through an array
- Use length, substring, ASC and CHR
- Build a string from parts
Arrays
An array holds several values under one name.
Each item has an index, starting at 0.
scores = [12, 7, 19, 4]
print(scores[0])
print(scores[scores.length - 1])scores ← [12, 7, 19, 4]
OUTPUT scores[0]
OUTPUT scores[LEN(scores) - 1]scores = [12, 7, 19, 4]
print(scores[0])
print(scores[len(scores) - 1])This prints 12, then 4: the last index is always the length minus 1. A loop from 0 to length - 1 visits every item.
A 2D array is a table: grid[row, column] in OCR style, grid[row][column] in AQA style and Python. The first index picks the row. Rows and columns are both numbered from 0.
For grid = [[5, 8, 1], [7, 2, 9]], row 0 is 5, 8, 1 and row 1 is 7, 2, 9, so grid[1, 2] is row 1, column 2: the value 9. A loop for c = 0 to 2 adding grid[0, c] adds up row 0: 5 + 8 + 1 = 14.
The rest of this lesson and its 7 practice questions are locked.
In this lesson
- Arrays
- String handling
- Try it: Read an array
7 practice questions, marked as you go; about 25 minutes in all.
Key terms
Array, Index, Length, ASCII
In this unit: Programming
Data types, operators, selection, loops, arrays, strings, subroutines, robust programs, SQL and files, read and traced step by step.