布尔类型 #

true
false
typeof(true)
typeof(false)

true isa Integer
false isa Integer
Int(true)
Int(false)
true + true
true * 5

true == 1
false == 0
true === 1

1 == 1
1 == 2
1 != 2
"hello" == "hello"
[1, 2] == [1, 2]

1 < 2
2 > 1
1 <= 1
1 >= 1
"a" < "b"

1 < 2 < 3
1 < 2 > 1
1 < 3 == 3
1 < 2 < 3 < 4

NaN == NaN
NaN != NaN
isequal(NaN, NaN)
ismissing(missing)
missing === missing

!true
!false
!!true

true && true
true && false
false && true
false && false

true || true
true || false
false || true
false || false

~true
true & false
true | false
true ⊻ false

true && println("This prints")
false && println("This doesn't print")

function safe_divide(a, b)
    b != 0 && a / b
end

true || println("This doesn't print")
false || println("This prints")

function get_value(dict, key, default)
    haskey(dict, key) || return default
    dict[key]
end

x = 5
x > 0 && println("Positive")
x < 0 || println("Non-negative")

if true
    println("True")
end

Bool(1)
Bool(0)
Bool(0.0)
Bool(1.0)

x = nothing
x === nothing
isnothing(x)

isempty([])
isempty([1, 2, 3])
isempty("")
isempty("Hello")

condition ? value_if_true : value_if_false

x = 5
x > 0 ? "Positive" : "Non-positive"

x = 0
x > 0 ? "Positive" : x < 0 ? "Negative" : "Zero"

x = 5

result = x > 0 ? "Positive" : "Non-positive"

result = if x > 0
    "Positive"
else
    "Non-positive"
end

isa(1, Int)
isa(1.0, Int)
typeof(1) == Int

in(1, [1, 2, 3])
1 ∈ [1, 2, 3]
1 ∉ [1, 2, 3]

in(5, 1:10)
5 in 1:10

occursin("Julia", "Hello Julia")
startswith("Hello Julia", "Hello")
endswith("Hello Julia", "Julia")
contains("Hello Julia", "Julia")

function classify_number(n)
    n > 0 ? "Positive" : n < 0 ? "Negative" : "Zero"
end

classify_number(5)
classify_number(-3)
classify_number(0)

function safe_sqrt(x)
    x >= 0 && return sqrt(x)
    return nothing
end

safe_sqrt(4)
safe_sqrt(-1)

function is_valid_age(age)
    age >= 0 && age <= 120
end

function can_vote(age, citizenship)
    age >= 18 && citizenship == "citizen"
end

is_valid_age(25)
can_vote(20, "citizen")

function process(x)
    x < 0 && return "Negative"
    x == 0 && return "Zero"
    x > 100 && return "Large"
    return "Small positive"
end

process(-5)
process(0)
process(50)
process(150)