Control Flow Details

If Else Branches

Lua if and else branches choose one of two paths.

two branches The condition controls which assignment runs before the shared output.

If Else Branches

score
if_else_branches.lua
Replay: real traced execution (multi-file project)
local score = 82
local result = ""

if score >= 80 then
  result = "pass"
else
  result = "review"
end

print("score=" .. score)
print("result=" .. result)

local score = 65
local result = ""

if score >= 80 then
  result = "pass"
else
  result = "review"
end

print("score=" .. score)
print("result=" .. result)

local score = 95
local result = ""

if score >= 80 then
  result = "pass"
else
  result = "review"
end

print("score=" .. score)
print("result=" .. result)

  1. score ← 82, result ← (empty)

    1local score→ 82 = 82 --@score=65, 952local result→ (empty) = ""

  2. result ← pass

    4if score82 >= 80 then5  result→ pass = "pass"6else

  3. print("score=" .. score)

    10print("score=" .. score82)11print("result=" .. resultpass)
    outputscore=82
result=pass

  1. score ← 65, result ← (empty)

    1local score→ 65 = 652local result→ (empty) = ""

  2. result ← review

    5  result = "pass"6else7  result→ review = "review"8end

  3. print("score=" .. score)

    10print("score=" .. score65)11print("result=" .. resultreview)
    outputscore=65
result=review

  1. score ← 95, result ← (empty)

    1local score→ 95 = 952local result→ (empty) = ""

  2. result ← pass

    4if score95 >= 80 then5  result→ pass = "pass"6else

  3. print("score=" .. score)

    10print("score=" .. score95)11print("result=" .. resultpass)
    outputscore=95
result=pass

Choose Pass or Review

  1. score starts at 82.
  2. The check score >= 80 is true.
  3. The if branch runs.
  4. result becomes pass. | Score | Branch | Result | | --- | --- | --- | | 65 | else | review | | 82 | if | pass | | 95 | if | pass |

Exercise: if_else_branches.lua

Use if and else to print pass for scores at least 80 and review otherwise