. 242 47 融會貫通 - 練習 243 48 練習題的參考答案 244 XI 裸機開發：上午 245 49 歡迎瞭解 Rust 裸機開發 246 50 no_std 247 50.1 最簡單的 no_std 程式 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 50.2 alloc . . . 標準程式庫包含各式實用巨集。 • println!(format, ..) prints a line to standard output, applying formatting described in std::fmt. • format!(format, ..) 的運作方式與 println! 類似，但會以字串形式傳回結果。 • dbg!(expression) 會記錄並傳回運算式的值。 • todo 等於size_of::>(). 如果想示範位元表示法實際運作時「可能」的樣子，可以使用下列範例程式碼。請務必注意，編譯器並 無對這個表示法提供保證，因此這完全不安全。 use std::mem::transmute; macro_rules! dbg_bits { ($e:expr, $bit_type:ty) => { println!("- {}: {:#x}", stringify

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 19.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} of any hard scope construct (i.e. within a let block, function or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 19.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 19.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} of any hard scope construct (i.e. within a let block, function or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} of any hard scope construct (i.e. within a let block, function or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} of any hard scope construct (i.e. within a let block, function or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} hard scope construct (i.e. within a let block, function, struct or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} hard scope construct (i.e. within a let block, function, struct or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} hard scope construct (i.e. within a let block, function, struct or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} hard scope construct (i.e. within a let block, function, struct or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already

Comprehensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.5 Generator Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280 20.6 Indexing map(abs2, 1:4) Base.Generator{UnitRange{Int64}, typeof(abs2)}(abs2, 1:4) julia> a 1 julia> b Base.Iterators.Rest{Base.Generator{UnitRange{Int64}, typeof(abs2)}, Int64}(Base.Generator{UnitRange{Int64} hard scope construct (i.e. within a let block, function, struct or macro body, comprehension, or generator), a new local named x is created in the scope of the assignment; 3. Soft scope: If x is not already