Values and Types

Numbers

Lua numbers handle arithmetic for counts, totals, and simple measurements.

arithmetic Number expressions combine values with operators such as `+`, `-`, `*`, and `/`.

Numbers

apples
numbers.lua
Replay: real traced execution (multi-file project)
local apples = 7
local oranges = 5
local total = apples + oranges
local average = total / 2

print("apples=" .. apples)
print("total=" .. total)
print("average=" .. average)

local apples = 3
local oranges = 5
local total = apples + oranges
local average = total / 2

print("apples=" .. apples)
print("total=" .. total)
print("average=" .. average)

local apples = 10
local oranges = 5
local total = apples + oranges
local average = total / 2

print("apples=" .. apples)
print("total=" .. total)
print("average=" .. average)

  1. apples ← 7, oranges ← 5, total ← 12, average ← 6.0

    1local apples→ 7 = 7 --@apples=3, 102local oranges→ 5 = 53local total→ 12 = apples7 + oranges54local average→ 6.0 = total12 / 256print("apples=" .. apples7)7print("total=" .. total12)8print("average=" .. average6.0)
    outputapples=7
total=12
average=6.0

  1. apples ← 3, oranges ← 5, total ← 8, average ← 4.0

    1local apples→ 3 = 32local oranges→ 5 = 53local total→ 8 = apples3 + oranges54local average→ 4.0 = total8 / 256print("apples=" .. apples3)7print("total=" .. total8)8print("average=" .. average4.0)
    outputapples=3
total=8
average=4.0

  1. apples ← 10, oranges ← 5, total ← 15, average ← 7.5

    1local apples→ 10 = 102local oranges→ 5 = 53local total→ 15 = apples10 + oranges54local average→ 7.5 = total15 / 256print("apples=" .. apples10)7print("total=" .. total15)8print("average=" .. average7.5)
    outputapples=10
total=15
average=7.5

Follow the Values

  1. apples starts at 7.
  2. oranges is 5.
  3. total = apples + oranges becomes 12.
  4. average = total / 2 becomes 6.0.
  5. The program prints apples=7, total=12, and average=6.0. | apples | oranges | total | average | | --- | --- | --- | --- | | 3 | 5 | 8 | 4.0 | | 7 | 5 | 12 | 6.0 | | 10 | 5 | 15 | 7.5 |

Exercise: numbers.lua

Reproduce average=6.0, then use apples 3 and 10 to predict each total and average.