mirror of
https://github.com/adambard/learnxinyminutes-docs.git
synced 2024-12-23 17:41:41 +00:00
Update to Julia 1.0 (Finish 3/6)
This commit is contained in:
0u0
parent
440247a597
commit
3a76acef98
@ -5,10 +5,11 @@ contributors:
|
||||
- ["Jichao Ouyang", "http://oyanglul.us"]
|
||||
translators:
|
||||
- ["Jichao Ouyang", "http://oyanglul.us"]
|
||||
- ["woclass", "https://github.com/inkydragon"]
|
||||
lang: zh-cn
|
||||
---
|
||||
|
||||
```ruby
|
||||
```julia
|
||||
# 单行注释只需要一个井号
|
||||
#= 多行注释
|
||||
只需要以 '#=' 开始 '=#' 结束
|
||||
@ -19,41 +20,41 @@ lang: zh-cn
|
||||
## 1. 原始类型与操作符
|
||||
####################################################
|
||||
|
||||
# Julia 中一切皆是表达式。
|
||||
# Julia 中一切皆为表达式
|
||||
|
||||
# 这是一些基本数字类型.
|
||||
3 # => 3 (Int64)
|
||||
3.2 # => 3.2 (Float64)
|
||||
2 + 1im # => 2 + 1im (Complex{Int64})
|
||||
2//3 # => 2//3 (Rational{Int64})
|
||||
# 这是一些基本数字类型
|
||||
typeof(3) # => Int64
|
||||
typeof(3.2) # => Float64
|
||||
typeof(2 + 1im) # => Complex{Int64}
|
||||
typeof(2 // 3) # => Rational{Int64}
|
||||
|
||||
# 支持所有的普通中缀操作符。
|
||||
1 + 1 # => 2
|
||||
8 - 1 # => 7
|
||||
10 * 2 # => 20
|
||||
35 / 5 # => 7.0
|
||||
5 / 2 # => 2.5 # 用 Int 除 Int 永远返回 Float
|
||||
div(5, 2) # => 2 # 使用 div 截断小数点
|
||||
5 \ 35 # => 7.0
|
||||
2 ^ 2 # => 4 # 次方, 不是二进制 xor
|
||||
12 % 10 # => 2
|
||||
# 支持所有的普通中缀操作符
|
||||
1 + 1 # => 2
|
||||
8 - 1 # => 7
|
||||
10 * 2 # => 20
|
||||
35 / 5 # => 7.0
|
||||
10 / 2 # => 5.0 # 整数除法总是返回浮点数
|
||||
div(5, 2) # => 2 # 使用 div 可以获得整除的结果
|
||||
5 \ 35 # => 7.0
|
||||
2^2 # => 4 # 幂运算，不是异或 (xor)
|
||||
12 % 10 # => 2
|
||||
|
||||
# 用括号提高优先级
|
||||
(1 + 3) * 2 # => 8
|
||||
|
||||
# 二进制操作符
|
||||
~2 # => -3 # 非
|
||||
3 & 5 # => 1 # 与
|
||||
2 | 4 # => 6 # 或
|
||||
2 $ 4 # => 6 # 异或
|
||||
2 >>> 1 # => 1 # 逻辑右移
|
||||
2 >> 1 # => 1 # 算术右移
|
||||
2 << 1 # => 4 # 逻辑/算术 右移
|
||||
# 位操作符
|
||||
~2 # => -3 # 按位非 (not)
|
||||
3 & 5 # => 1 # 按位与 (and)
|
||||
2 | 4 # => 6 # 按位或 (or)
|
||||
xor(2, 4) # => 6 # 按位异或 (xor)
|
||||
2 >>> 1 # => 1 # 逻辑右移
|
||||
2 >> 1 # => 1 # 算术右移
|
||||
2 << 1 # => 4 # 逻辑/算术左移
|
||||
|
||||
# 可以用函数 bits 查看二进制数。
|
||||
bits(12345)
|
||||
# 可以用函数 bitstring 查看二进制数。
|
||||
bitstring(12345)
|
||||
# => "0000000000000000000000000000000000000000000000000011000000111001"
|
||||
bits(12345.0)
|
||||
bitstring(12345.0)
|
||||
# => "0100000011001000000111001000000000000000000000000000000000000000"
|
||||
|
||||
# 布尔值是原始类型
|
||||
@ -61,17 +62,18 @@ true
|
||||
false
|
||||
|
||||
# 布尔操作符
|
||||
!true # => false
|
||||
!false # => true
|
||||
1 == 1 # => true
|
||||
2 == 1 # => false
|
||||
1 != 1 # => false
|
||||
2 != 1 # => true
|
||||
1 < 10 # => true
|
||||
1 > 10 # => false
|
||||
2 <= 2 # => true
|
||||
2 >= 2 # => true
|
||||
# 比较可以串联
|
||||
!true # => false
|
||||
!false # => true
|
||||
1 == 1 # => true
|
||||
2 == 1 # => false
|
||||
1 != 1 # => false
|
||||
2 != 1 # => true
|
||||
1 < 10 # => true
|
||||
1 > 10 # => false
|
||||
2 <= 2 # => true
|
||||
2 >= 2 # => true
|
||||
|
||||
# 链式比较
|
||||
1 < 2 < 3 # => true
|
||||
2 < 3 < 2 # => false
|
||||
|
||||
@ -82,7 +84,8 @@ false
|
||||
'a'
|
||||
|
||||
# 可以像取数组取值一样用 index 取出对应字符
|
||||
"This is a string"[1] # => 'T' # Julia 的 index 从 1 开始 :(
|
||||
ascii("This is a string")[1] # => 'T'
|
||||
# Julia 的 index 从 1 开始 :(
|
||||
# 但是对 UTF-8 无效,
|
||||
# 因此建议使用遍历器 (map, for loops, 等).
|
||||
|
||||
@ -90,12 +93,18 @@ false
|
||||
"2 + 2 = $(2 + 2)" # => "2 + 2 = 4"
|
||||
# 可以将任何 Julia 表达式放入括号。
|
||||
|
||||
# 另一种格式化字符串的方式是 printf 宏.
|
||||
@printf "%d is less than %f" 4.5 5.3 # 5 is less than 5.300000
|
||||
# 另一种输出格式化字符串的方法是使用标准库 Printf 中的 Printf 宏
|
||||
using Printf
|
||||
@printf "%d is less than %f\n" 4.5 5.3 # => 5 is less than 5.300000
|
||||
|
||||
# 打印字符串很容易
|
||||
println("I'm Julia. Nice to meet you!")
|
||||
|
||||
# 字符串可以按字典序进行比较
|
||||
"good" > "bye" # => true
|
||||
"good" == "good" # => true
|
||||
"1 + 2 = 3" == "1 + 2 = $(1 + 2)" # => true
|
||||
|
||||
####################################################
|
||||
## 2. 变量与集合
|
||||
####################################################
|
||||
@ -106,12 +115,12 @@ some_var # => 5
|
||||
|
||||
# 访问未声明变量会抛出异常
|
||||
try
|
||||
some_other_var # => ERROR: some_other_var not defined
|
||||
some_other_var # => ERROR: UndefVarError: some_other_var not defined
|
||||
catch e
|
||||
println(e)
|
||||
end
|
||||
|
||||
# 变量名需要以字母开头.
|
||||
# 变量名必须以下划线或字母开头
|
||||
# 之后任何字母，数字，下划线，叹号都是合法的。
|
||||
SomeOtherVar123! = 6 # => 6
|
||||
|
||||
@ -122,7 +131,7 @@ SomeOtherVar123! = 6 # => 6
|
||||
|
||||
# 注意 Julia 的命名规约:
|
||||
#
|
||||
# * 变量名为小写，单词之间以下划线连接('\_')。
|
||||
# * 变量名为小写，单词之间以下划线连接 "_" 。
|
||||
#
|
||||
# * 类型名以大写字母开头，单词以 CamelCase 方式连接。
|
||||
#
|
||||
@ -131,57 +140,81 @@ SomeOtherVar123! = 6 # => 6
|
||||
# * 会改变输入的函数名末位为 !。
|
||||
# 这类函数有时被称为 mutating functions 或 in-place functions.
|
||||
|
||||
# 数组存储一列值，index 从 1 开始。
|
||||
a = Int64[] # => 0-element Int64 Array
|
||||
# 数组存储一列值，index 从 1 开始
|
||||
a = Int64[] # => 0-element Array{Int64,1}
|
||||
|
||||
# 一维数组可以以逗号分隔值的方式声明。
|
||||
b = [4, 5, 6] # => 包含 3 个 Int64 类型元素的数组: [4, 5, 6]
|
||||
b[1] # => 4
|
||||
b[end] # => 6
|
||||
# 一维数组可以以逗号分隔值的方式声明
|
||||
b = [4, 5, 6] # => 3-element Array{Int64,1}: [4, 5, 6]
|
||||
b = [4; 5; 6] # => 3-element Array{Int64,1}: [4, 5, 6]
|
||||
b[1] # => 4
|
||||
b[end] # => 6
|
||||
|
||||
# 二维数组以分号分隔维度。
|
||||
matrix = [1 2; 3 4] # => 2x2 Int64 数组: [1 2; 3 4]
|
||||
# 二维数组以分号分隔维度
|
||||
matrix = [1 2; 3 4] # => 2×2 Array{Int64,2}: [1 2; 3 4]
|
||||
|
||||
# 指定数组的类型
|
||||
b = Int8[4, 5, 6] # => 3-element Array{Int8,1}: [4, 5, 6]
|
||||
|
||||
# 使用 push! 和 append! 往数组末尾添加元素
|
||||
push!(a,1) # => [1]
|
||||
push!(a,2) # => [1,2]
|
||||
push!(a,4) # => [1,2,4]
|
||||
push!(a,3) # => [1,2,4,3]
|
||||
append!(a,b) # => [1,2,4,3,4,5,6]
|
||||
push!(a, 1) # => [1]
|
||||
push!(a, 2) # => [1,2]
|
||||
push!(a, 4) # => [1,2,4]
|
||||
push!(a, 3) # => [1,2,4,3]
|
||||
append!(a, b) # => [1,2,4,3,4,5,6]
|
||||
|
||||
# 用 pop 弹出末尾元素
|
||||
pop!(b) # => 6 and b is now [4,5]
|
||||
# 用 pop 弹出尾部的元素
|
||||
pop!(b) # => 6
|
||||
b # => [4,5]
|
||||
|
||||
# 可以再放回去
|
||||
push!(b,6) # b 又变成了 [4,5,6].
|
||||
# 再放回去
|
||||
push!(b, 6) # => [4,5,6]
|
||||
b # => [4,5,6]
|
||||
|
||||
a[1] # => 1 # 永远记住 Julia 的 index 从 1 开始!
|
||||
a[1] # => 1 # 永远记住 Julia 的引索从 1 开始！而不是 0！
|
||||
|
||||
# 用 end 可以直接取到最后索引. 可用作任何索引表达式
|
||||
a[end] # => 6
|
||||
|
||||
# 还支持 shift 和 unshift
|
||||
shift!(a) # => 返回 1，而 a 现在时 [2,4,3,4,5,6]
|
||||
unshift!(a,7) # => [7,2,4,3,4,5,6]
|
||||
# 数组还支持 popfirst! 和 pushfirst!
|
||||
popfirst!(a) # => 1
|
||||
a # => [2,4,3,4,5,6]
|
||||
pushfirst!(a, 7) # => [7,2,4,3,4,5,6]
|
||||
a # => [7,2,4,3,4,5,6]
|
||||
|
||||
# 以叹号结尾的函数名表示它会改变参数的值
|
||||
arr = [5,4,6] # => 包含三个 Int64 元素的数组: [5,4,6]
|
||||
sort(arr) # => [4,5,6]; arr 还是 [5,4,6]
|
||||
sort!(arr) # => [4,5,6]; arr 现在是 [4,5,6]
|
||||
arr = [5,4,6] # => 3-element Array{Int64,1}: [5,4,6]
|
||||
sort(arr) # => [4,5,6]
|
||||
arr # => [5,4,6]
|
||||
sort!(arr) # => [4,5,6]
|
||||
arr # => [4,5,6]
|
||||
|
||||
# 越界会抛出 BoundsError 异常
|
||||
# 数组越界会抛出 BoundsError
|
||||
try
|
||||
a[0] # => ERROR: BoundsError() in getindex at array.jl:270
|
||||
a[end+1] # => ERROR: BoundsError() in getindex at array.jl:270
|
||||
a[0]
|
||||
# => ERROR: BoundsError: attempt to access 7-element Array{Int64,1} at
|
||||
# index [0]
|
||||
# => Stacktrace:
|
||||
# => [1] getindex(::Array{Int64,1}, ::Int64) at .\array.jl:731
|
||||
# => [2] top-level scope at none:0
|
||||
# => [3] ...
|
||||
# => in expression starting at ...\LearnJulia.jl:188
|
||||
a[end + 1]
|
||||
# => ERROR: BoundsError: attempt to access 7-element Array{Int64,1} at
|
||||
# index [8]
|
||||
# => Stacktrace:
|
||||
# => [1] getindex(::Array{Int64,1}, ::Int64) at .\array.jl:731
|
||||
# => [2] top-level scope at none:0
|
||||
# => [3] ...
|
||||
# => in expression starting at ...\LearnJulia.jl:196
|
||||
catch e
|
||||
println(e)
|
||||
end
|
||||
|
||||
# 错误会指出发生的行号，包括标准库
|
||||
# 如果你有 Julia 源代码，你可以找到这些地方
|
||||
# 报错时错误会指出出错的文件位置以及行号，标准库也一样
|
||||
# 你可以在 Julia 安装目录下的 share/julia 文件夹里找到这些标准库
|
||||
|
||||
# 可以用 range 初始化数组
|
||||
a = [1:5] # => 5-element Int64 Array: [1,2,3,4,5]
|
||||
a = [1:5;] # => 5-element Array{Int64,1}: [1,2,3,4,5]
|
||||
|
||||
# 可以切割数组
|
||||
a[1:3] # => [1, 2, 3]
|
||||
@ -189,11 +222,13 @@ a[2:end] # => [2, 3, 4, 5]
|
||||
|
||||
# 用 splice! 切割原数组
|
||||
arr = [3,4,5]
|
||||
splice!(arr,2) # => 4 ; arr 变成了 [3,5]
|
||||
splice!(arr, 2) # => 4
|
||||
arr # => [3,5]
|
||||
|
||||
# 用 append! 连接数组
|
||||
b = [1,2,3]
|
||||
append!(a,b) # a 变成了 [1, 2, 3, 4, 5, 1, 2, 3]
|
||||
append!(a, b) # => [1, 2, 3, 4, 5, 1, 2, 3]
|
||||
a # => [1, 2, 3, 4, 5, 1, 2, 3]
|
||||
|
||||
# 检查元素是否在数组中
|
||||
in(1, a) # => true
|
||||
@ -201,162 +236,174 @@ in(1, a) # => true
|
||||
# 用 length 获得数组长度
|
||||
length(a) # => 8
|
||||
|
||||
# Tuples 是 immutable 的
|
||||
tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
|
||||
# 元组(Tuples)是不可变的
|
||||
tup = (1, 2, 3) # => (1,2,3)
|
||||
typeof(tup) # => Tuple{Int64,Int64,Int64}
|
||||
tup[1] # => 1
|
||||
try:
|
||||
tup[1] = 3 # => ERROR: no method setindex!((Int64,Int64,Int64),Int64,Int64)
|
||||
try
|
||||
tup[1] = 3
|
||||
# => ERROR: MethodError: no method matching
|
||||
# setindex!(::Tuple{Int64,Int64,Int64}, ::Int64, ::Int64)
|
||||
catch e
|
||||
println(e)
|
||||
end
|
||||
|
||||
# 大多数组的函数同样支持 tuples
|
||||
# 大多数组的函数同样支持元组
|
||||
length(tup) # => 3
|
||||
tup[1:2] # => (1,2)
|
||||
in(2, tup) # => true
|
||||
tup[1:2] # => (1,2)
|
||||
in(2, tup) # => true
|
||||
|
||||
# 可以将 tuples 元素分别赋给变量
|
||||
a, b, c = (1, 2, 3) # => (1,2,3) # a is now 1, b is now 2 and c is now 3
|
||||
# 可以将元组的元素解包赋给变量
|
||||
a, b, c = (1, 2, 3) # => (1,2,3)
|
||||
a # => 1
|
||||
b # => 2
|
||||
c # => 3
|
||||
|
||||
# 不用括号也可以
|
||||
d, e, f = 4, 5, 6 # => (4,5,6)
|
||||
d, e, f = 4, 5, 6 # => (4,5,6)
|
||||
d # => 4
|
||||
e # => 5
|
||||
f # => 6
|
||||
|
||||
# 单元素 tuple 不等于其元素值
|
||||
(1,) == 1 # => false
|
||||
(1) == 1 # => true
|
||||
(1) == 1 # => true
|
||||
|
||||
# 交换值
|
||||
e, d = d, e # => (5,4) # d is now 5 and e is now 4
|
||||
e, d = d, e # => (5,4)
|
||||
d # => 5
|
||||
e # => 4
|
||||
|
||||
|
||||
# 字典Dictionaries store mappings
|
||||
empty_dict = Dict() # => Dict{Any,Any}()
|
||||
empty_dict = Dict() # => Dict{Any,Any} with 0 entries
|
||||
|
||||
# 也可以用字面量创建字典
|
||||
filled_dict = ["one"=> 1, "two"=> 2, "three"=> 3]
|
||||
# => Dict{ASCIIString,Int64}
|
||||
filled_dict = Dict("one" => 1, "two" => 2, "three" => 3)
|
||||
# => Dict{String,Int64} with 3 entries:
|
||||
# => "two" => 2, "one" => 1, "three" => 3
|
||||
|
||||
# 用 [] 获得键值
|
||||
filled_dict["one"] # => 1
|
||||
|
||||
# 获得所有键
|
||||
keys(filled_dict)
|
||||
# => KeyIterator{Dict{ASCIIString,Int64}}(["three"=>3,"one"=>1,"two"=>2])
|
||||
# => Base.KeySet for a Dict{String,Int64} with 3 entries. Keys:
|
||||
# => "two", "one", "three"
|
||||
# 注意，键的顺序不是插入时的顺序
|
||||
|
||||
# 获得所有值
|
||||
values(filled_dict)
|
||||
# => ValueIterator{Dict{ASCIIString,Int64}}(["three"=>3,"one"=>1,"two"=>2])
|
||||
# => Base.ValueIterator for a Dict{String,Int64} with 3 entries. Values:
|
||||
# => 2, 1, 3
|
||||
# 注意，值的顺序也一样
|
||||
|
||||
# 用 in 检查键值是否已存在，用 haskey 检查键是否存在
|
||||
in(("one", 1), filled_dict) # => true
|
||||
in(("two", 3), filled_dict) # => false
|
||||
haskey(filled_dict, "one") # => true
|
||||
haskey(filled_dict, 1) # => false
|
||||
in(("one" => 1), filled_dict) # => true
|
||||
in(("two" => 3), filled_dict) # => false
|
||||
haskey(filled_dict, "one") # => true
|
||||
haskey(filled_dict, 1) # => false
|
||||
|
||||
# 获取不存在的键的值会抛出异常
|
||||
try
|
||||
filled_dict["four"] # => ERROR: key not found: four in getindex at dict.jl:489
|
||||
filled_dict["four"] # => ERROR: KeyError: key "four" not found
|
||||
catch e
|
||||
println(e)
|
||||
end
|
||||
|
||||
# 使用 get 可以提供默认值来避免异常
|
||||
# get(dictionary,key,default_value)
|
||||
get(filled_dict,"one",4) # => 1
|
||||
get(filled_dict,"four",4) # => 4
|
||||
get(filled_dict, "one", 4) # => 1
|
||||
get(filled_dict, "four", 4) # => 4
|
||||
|
||||
# 用 Sets 表示无序不可重复的值的集合
|
||||
empty_set = Set() # => Set{Any}()
|
||||
# 初始化一个 Set 并定义其值
|
||||
filled_set = Set(1,2,2,3,4) # => Set{Int64}(1,2,3,4)
|
||||
# Sets 表示无序不可重复的值的集合
|
||||
empty_set = Set() # => Set(Any[])
|
||||
# 初始化一个带初值的 Set
|
||||
filled_set = Set([1, 2, 2, 3, 4]) # => Set([4, 2, 3, 1])
|
||||
|
||||
# 添加值
|
||||
push!(filled_set,5) # => Set{Int64}(5,4,2,3,1)
|
||||
# 新增值
|
||||
push!(filled_set, 5) # => Set([4, 2, 3, 5, 1])
|
||||
|
||||
# 检查是否存在某值
|
||||
in(2, filled_set) # => true
|
||||
in(10, filled_set) # => false
|
||||
# 检查 Set 中是否存在某值
|
||||
in(2, filled_set) # => true
|
||||
in(10, filled_set) # => false
|
||||
|
||||
# 交集，并集，差集
|
||||
other_set = Set(3, 4, 5, 6) # => Set{Int64}(6,4,5,3)
|
||||
intersect(filled_set, other_set) # => Set{Int64}(3,4,5)
|
||||
union(filled_set, other_set) # => Set{Int64}(1,2,3,4,5,6)
|
||||
setdiff(Set(1,2,3,4),Set(2,3,5)) # => Set{Int64}(1,4)
|
||||
other_set = Set([3, 4, 5, 6]) # => Set([4, 3, 5, 6])
|
||||
intersect(filled_set, other_set) # => Set([4, 3, 5])
|
||||
union(filled_set, other_set) # => Set([4, 2, 3, 5, 6, 1])
|
||||
setdiff(Set([1,2,3,4]), Set([2,3,5])) # => Set([4, 1])
|
||||
|
||||
|
||||
####################################################
|
||||
## 3. 控制流
|
||||
## 3. 控制语句
|
||||
####################################################
|
||||
|
||||
# 声明一个变量
|
||||
some_var = 5
|
||||
|
||||
# 这是一个 if 语句，缩进不是必要的
|
||||
# 这是一个 if 语句块，其中的缩进不是必须的
|
||||
if some_var > 10
|
||||
println("some_var is totally bigger than 10.")
|
||||
elseif some_var < 10 # elseif 是可选的.
|
||||
elseif some_var < 10 # elseif 是可选的
|
||||
println("some_var is smaller than 10.")
|
||||
else # else 也是可选的.
|
||||
else # else 也是可选的
|
||||
println("some_var is indeed 10.")
|
||||
end
|
||||
# => prints "some var is smaller than 10"
|
||||
# => some_var is smaller than 10.
|
||||
|
||||
|
||||
# For 循环遍历
|
||||
# Iterable 类型包括 Range, Array, Set, Dict, 以及 String.
|
||||
for animal=["dog", "cat", "mouse"]
|
||||
# 可迭代的类型包括：Range, Array, Set, Dict 和 AbstractString
|
||||
for animal = ["dog", "cat", "mouse"]
|
||||
println("$animal is a mammal")
|
||||
# 可用 $ 将 variables 或 expression 转换为字符串into strings
|
||||
# 你可以用 $ 将变量或表达式插入字符串中
|
||||
end
|
||||
# prints:
|
||||
# dog is a mammal
|
||||
# cat is a mammal
|
||||
# mouse is a mammal
|
||||
# => dog is a mammal
|
||||
# => cat is a mammal
|
||||
# => mouse is a mammal
|
||||
|
||||
# You can use 'in' instead of '='.
|
||||
# 你也可以不用 '=' 而使用 'in'
|
||||
for animal in ["dog", "cat", "mouse"]
|
||||
println("$animal is a mammal")
|
||||
end
|
||||
# prints:
|
||||
# dog is a mammal
|
||||
# cat is a mammal
|
||||
# mouse is a mammal
|
||||
# => dog is a mammal
|
||||
# => cat is a mammal
|
||||
# => mouse is a mammal
|
||||
|
||||
for a in ["dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal"]
|
||||
println("$(a[1]) is a $(a[2])")
|
||||
for pair in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal")
|
||||
from, to = pair
|
||||
println("$from is a $to")
|
||||
end
|
||||
# prints:
|
||||
# dog is a mammal
|
||||
# cat is a mammal
|
||||
# mouse is a mammal
|
||||
# => mouse is a mammal
|
||||
# => cat is a mammal
|
||||
# => dog is a mammal
|
||||
# 注意！这里的输出顺序和上面的不同
|
||||
|
||||
for (k,v) in ["dog"=>"mammal","cat"=>"mammal","mouse"=>"mammal"]
|
||||
for (k, v) in Dict("dog" => "mammal", "cat" => "mammal", "mouse" => "mammal")
|
||||
println("$k is a $v")
|
||||
end
|
||||
# prints:
|
||||
# dog is a mammal
|
||||
# cat is a mammal
|
||||
# mouse is a mammal
|
||||
# => mouse is a mammal
|
||||
# => cat is a mammal
|
||||
# => dog is a mammal
|
||||
|
||||
# While 循环
|
||||
x = 0
|
||||
while x < 4
|
||||
println(x)
|
||||
x += 1 # x = x + 1
|
||||
let x = 0
|
||||
while x < 4
|
||||
println(x)
|
||||
x += 1 # x = x + 1 的缩写
|
||||
end
|
||||
end
|
||||
# prints:
|
||||
# 0
|
||||
# 1
|
||||
# 2
|
||||
# 3
|
||||
# => 0
|
||||
# => 1
|
||||
# => 2
|
||||
# => 3
|
||||
|
||||
# 用 try/catch 处理异常
|
||||
try
|
||||
error("help")
|
||||
error("help")
|
||||
catch e
|
||||
println("caught it $e")
|
||||
println("caught it $e")
|
||||
end
|
||||
# => caught it ErrorException("help")
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user