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< ol class = "chapter" > < li class = "chapter-item expanded affix " > < a href = "../index.html" > Go语言圣经< / a > < / li > < li class = "chapter-item expanded affix " > < a href = "../preface.html" > 前言< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1.html" > < strong aria-hidden = "true" > 1.< / strong > 入门< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-01.html" > < strong aria-hidden = "true" > 1.1.< / strong > Hello, World< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-02.html" > < strong aria-hidden = "true" > 1.2.< / strong > 命令行参数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-03.html" > < strong aria-hidden = "true" > 1.3.< / strong > 查找重复的行< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-04.html" > < strong aria-hidden = "true" > 1.4.< / strong > GIF动画< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-05.html" > < strong aria-hidden = "true" > 1.5.< / strong > 获取URL< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-06.html" > < strong aria-hidden = "true" > 1.6.< / strong > 并发获取多个URL< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-07.html" > < strong aria-hidden = "true" > 1.7.< / strong > Web服务< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch1/ch1-08.html" > < strong aria-hidden = "true" > 1.8.< / strong > 本章要点< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2.html" > < strong aria-hidden = "true" > 2.< / strong > 程序结构< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-01.html" > < strong aria-hidden = "true" > 2.1.< / strong > 命名< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-02.html" > < strong aria-hidden = "true" > 2.2.< / strong > 声明< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-03.html" > < strong aria-hidden = "true" > 2.3.< / strong > 变量< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-04.html" > < strong aria-hidden = "true" > 2.4.< / strong > 赋值< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-05.html" > < strong aria-hidden = "true" > 2.5.< / strong > 类型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-06.html" > < strong aria-hidden = "true" > 2.6.< / strong > 包和文件< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch2/ch2-07.html" > < strong aria-hidden = "true" > 2.7.< / strong > 作用域< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3.html" > < strong aria-hidden = "true" > 3.< / strong > 基础数据类型< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-01.html" > < strong aria-hidden = "true" > 3.1.< / strong > 整型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-02.html" > < strong aria-hidden = "true" > 3.2.< / strong > 浮点数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-03.html" > < strong aria-hidden = "true" > 3.3.< / strong > 复数< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-04.html" > < strong aria-hidden = "true" > 3.4.< / strong > 布尔型< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-05.html" > < strong aria-hidden = "true" > 3.5.< / strong > 字符串< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch3/ch3-06.html" > < strong aria-hidden = "true" > 3.6.< / strong > 常量< / a > < / li > < / ol > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4.html" > < strong aria-hidden = "true" > 4.< / strong > 复合数据类型< / a > < / li > < li > < ol class = "section" > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-01.html" > < strong aria-hidden = "true" > 4.1.< / strong > 数组< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-02.html" > < strong aria-hidden = "true" > 4.2.< / strong > Slice< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-03.html" > < strong aria-hidden = "true" > 4.3.< / strong > Map< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-04.html" > < strong aria-hidden = "true" > 4.4.< / strong > 结构体< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-05.html" > < strong aria-hidden = "true" > 4.5.< / strong > JSON< / a > < / li > < li class = "chapter-item expanded " > < a href = "../ch4/ch4-06.html" > < strong aria-hidd
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2022-08-24 10:48:15 +00:00
< li > < em > KusonStack一站式可编程配置技术栈(Go): < a href = "https://github.com/KusionStack/kusion" > https://github.com/KusionStack/kusion< / a > < / em > < / li >
< li > < em > KCL 配置编程语言(Rust): < a href = "https://github.com/KusionStack/KCLVM" > https://github.com/KusionStack/KCLVM< / a > < / em > < / li >
< li > < em > 凹语言™: < a href = "https://github.com/wa-lang/wa" > https://github.com/wa-lang/wa< / a > < / em > < / li >
2022-08-04 06:59:33 +00:00
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< hr >
< h2 id = "65-示例-bit数组" > < a class = "header" href = "#65-示例-bit数组" > 6.5. 示例: Bit数组< / a > < / h2 >
< p > Go语言里的集合一般会用map[T]bool这种形式来表示， ， ， ， ， ， ， （ ： ， ， ， ， ） < / p >
< p > 一个bit数组通常会用一个无符号数或者称之为“字”的slice来表示， ， ， ： < / p >
< p > < u > < i > gopl.io/ch6/intset< / i > < / u > < / p >
< pre > < code class = "language-go" > // An IntSet is a set of small non-negative integers.
// Its zero value represents the empty set.
type IntSet struct {
words []uint64
}
// Has reports whether the set contains the non-negative value x.
func (s *IntSet) Has(x int) bool {
word, bit := x/64, uint(x%64)
return word < len(s.words) & & s.words[word]& (1< < bit) != 0
}
// Add adds the non-negative value x to the set.
func (s *IntSet) Add(x int) {
word, bit := x/64, uint(x%64)
for word > = len(s.words) {
s.words = append(s.words, 0)
}
s.words[word] |= 1 < < bit
}
// UnionWith sets s to the union of s and t.
func (s *IntSet) UnionWith(t *IntSet) {
for i, tword := range t.words {
if i < len(s.words) {
s.words[i] |= tword
} else {
s.words = append(s.words, tword)
}
}
}
< / code > < / pre >
< p > 因为每一个字都有64个二进制位， ， ， （ ） < / p >
< p > 当前这个实现还缺少了很多必要的特性， ： ， ， < / p >
< pre > < code class = "language-go" > // String returns the set as a string of the form " {1 2 3}" .
func (s *IntSet) String() string {
var buf bytes.Buffer
buf.WriteByte('{')
for i, word := range s.words {
if word == 0 {
continue
}
for j := 0; j < 64; j++ {
if word& (1< < uint(j)) != 0 {
if buf.Len() > len(" {" ) {
buf.WriteByte(' ')
}
fmt.Fprintf(& buf, " %d" , 64*i+j)
}
}
}
buf.WriteByte('}')
return buf.String()
}
< / code > < / pre >
< p > 这里留意一下String方法， ； ， ， ， ， < / p >
< p > 现在我们就可以在实战中直接用上面定义好的IntSet了： < / p >
< pre > < code class = "language-go" > var x, y IntSet
x.Add(1)
x.Add(144)
x.Add(9)
fmt.Println(x.String()) // " {1 9 144}"
y.Add(9)
y.Add(42)
fmt.Println(y.String()) // " {9 42}"
x.UnionWith(& y)
fmt.Println(x.String()) // " {1 9 42 144}"
fmt.Println(x.Has(9), x.Has(123)) // " true false"
< / code > < / pre >
< p > 这里要注意： < code > *IntSet< / code > 来作为接收器的， ， ， ， ， ， ， ， ， ： < / p >
< pre > < code class = "language-go" > fmt.Println(& x) // " {1 9 42 144}"
fmt.Println(x.String()) // " {1 9 42 144}"
fmt.Println(x) // " {[4398046511618 0 65536]}"
< / code > < / pre >
< p > 在第一个Println中， < code > *IntSet< / code > 的指针， ， ； & 操作符， ， ， & 符号是不能忘的。在我们这种场景下， ， ， < / p >
< p > < strong > 练习6.1:< / strong > 为bit数组实现下面这些方法< / p >
< pre > < code class = "language-go" > func (*IntSet) Len() int // return the number of elements
func (*IntSet) Remove(x int) // remove x from the set
func (*IntSet) Clear() // remove all elements from the set
func (*IntSet) Copy() *IntSet // return a copy of the set
< / code > < / pre >
< p > < strong > 练习 6.2： < / strong > 定义一个变参方法(*IntSet).AddAll(...int)， ， < / p >
< p > < strong > 练习 6.3： < / strong > (*IntSet).UnionWith会用< code > |< / code > 操作符计算两个集合的并集， （ ： ） ， （ ： ， ） ， （ ： ， ） < / p >
< p > ***练习6.4: ** 实现一个Elems方法， ， < / p >
< p > < strong > 练习 6.5： < / strong > 我们这章定义的IntSet里的每个字都是用的uint64类型， ， ， ， ， ， ： < < (^uint(0) > > 63)< / p >
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