gopl-zh.github.com/ch2/ch2-04.html
2015-12-16 10:56:29 +08:00

2182 lines
69 KiB
HTML

<!DOCTYPE HTML>
<html lang="zh-tw" >
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<title>賦值 | Go编程语言</title>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<meta name="generator" content="GitBook 2.5.2">
<meta name="HandheldFriendly" content="true"/>
<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<link rel="apple-touch-icon-precomposed" sizes="152x152" href="../gitbook/images/apple-touch-icon-precomposed-152.png">
<link rel="shortcut icon" href="../gitbook/images/favicon.ico" type="image/x-icon">
<link rel="stylesheet" href="../gitbook/style.css">
<link rel="stylesheet" href="../gitbook/plugins/gitbook-plugin-highlight/website.css">
<link rel="stylesheet" href="../gitbook/plugins/gitbook-plugin-search/search.css">
<link rel="stylesheet" href="../gitbook/plugins/gitbook-plugin-fontsettings/website.css">
<link rel="next" href="../ch2/ch2-05.html" />
<link rel="prev" href="../ch2/ch2-03.html" />
</head>
<body>
<div class="book" data-level="2.4" data-chapter-title="賦值" data-filepath="ch2/ch2-04.md" data-basepath=".." data-revision="Wed Dec 16 2015 10:54:29 GMT+0800 (中国标准时间)">
<div class="book-summary">
<nav role="navigation">
<ul class="summary">
<li class="chapter " data-level="0" data-path="index.html">
<a href="../index.html">
<i class="fa fa-check"></i>
前言
</a>
<ul class="articles">
<li class="chapter " data-level="0.1" data-path="ch0/ch0-01.html">
<a href="../ch0/ch0-01.html">
<i class="fa fa-check"></i>
<b>0.1.</b>
Go語言起源
</a>
</li>
<li class="chapter " data-level="0.2" data-path="ch0/ch0-02.html">
<a href="../ch0/ch0-02.html">
<i class="fa fa-check"></i>
<b>0.2.</b>
Go語言項目
</a>
</li>
<li class="chapter " data-level="0.3" data-path="ch0/ch0-03.html">
<a href="../ch0/ch0-03.html">
<i class="fa fa-check"></i>
<b>0.3.</b>
本書的組織
</a>
</li>
<li class="chapter " data-level="0.4" data-path="ch0/ch0-04.html">
<a href="../ch0/ch0-04.html">
<i class="fa fa-check"></i>
<b>0.4.</b>
更多的信息
</a>
</li>
<li class="chapter " data-level="0.5" data-path="ch0/ch0-05.html">
<a href="../ch0/ch0-05.html">
<i class="fa fa-check"></i>
<b>0.5.</b>
緻謝
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="1" data-path="ch1/ch1.html">
<a href="../ch1/ch1.html">
<i class="fa fa-check"></i>
<b>1.</b>
入門
</a>
<ul class="articles">
<li class="chapter " data-level="1.1" data-path="ch1/ch1-01.html">
<a href="../ch1/ch1-01.html">
<i class="fa fa-check"></i>
<b>1.1.</b>
Hello, World
</a>
</li>
<li class="chapter " data-level="1.2" data-path="ch1/ch1-02.html">
<a href="../ch1/ch1-02.html">
<i class="fa fa-check"></i>
<b>1.2.</b>
命令行參數
</a>
</li>
<li class="chapter " data-level="1.3" data-path="ch1/ch1-03.html">
<a href="../ch1/ch1-03.html">
<i class="fa fa-check"></i>
<b>1.3.</b>
査找重復的行
</a>
</li>
<li class="chapter " data-level="1.4" data-path="ch1/ch1-04.html">
<a href="../ch1/ch1-04.html">
<i class="fa fa-check"></i>
<b>1.4.</b>
GIF動畫
</a>
</li>
<li class="chapter " data-level="1.5" data-path="ch1/ch1-05.html">
<a href="../ch1/ch1-05.html">
<i class="fa fa-check"></i>
<b>1.5.</b>
穫取URL
</a>
</li>
<li class="chapter " data-level="1.6" data-path="ch1/ch1-06.html">
<a href="../ch1/ch1-06.html">
<i class="fa fa-check"></i>
<b>1.6.</b>
併髮穫取多個URL
</a>
</li>
<li class="chapter " data-level="1.7" data-path="ch1/ch1-07.html">
<a href="../ch1/ch1-07.html">
<i class="fa fa-check"></i>
<b>1.7.</b>
Web服務
</a>
</li>
<li class="chapter " data-level="1.8" data-path="ch1/ch1-08.html">
<a href="../ch1/ch1-08.html">
<i class="fa fa-check"></i>
<b>1.8.</b>
本章要點
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="2" data-path="ch2/ch2.html">
<a href="../ch2/ch2.html">
<i class="fa fa-check"></i>
<b>2.</b>
程序結構
</a>
<ul class="articles">
<li class="chapter " data-level="2.1" data-path="ch2/ch2-01.html">
<a href="../ch2/ch2-01.html">
<i class="fa fa-check"></i>
<b>2.1.</b>
命名
</a>
</li>
<li class="chapter " data-level="2.2" data-path="ch2/ch2-02.html">
<a href="../ch2/ch2-02.html">
<i class="fa fa-check"></i>
<b>2.2.</b>
聲明
</a>
</li>
<li class="chapter " data-level="2.3" data-path="ch2/ch2-03.html">
<a href="../ch2/ch2-03.html">
<i class="fa fa-check"></i>
<b>2.3.</b>
變量
</a>
</li>
<li class="chapter active" data-level="2.4" data-path="ch2/ch2-04.html">
<a href="../ch2/ch2-04.html">
<i class="fa fa-check"></i>
<b>2.4.</b>
賦值
</a>
</li>
<li class="chapter " data-level="2.5" data-path="ch2/ch2-05.html">
<a href="../ch2/ch2-05.html">
<i class="fa fa-check"></i>
<b>2.5.</b>
類型
</a>
</li>
<li class="chapter " data-level="2.6" data-path="ch2/ch2-06.html">
<a href="../ch2/ch2-06.html">
<i class="fa fa-check"></i>
<b>2.6.</b>
包和文件
</a>
</li>
<li class="chapter " data-level="2.7" data-path="ch2/ch2-07.html">
<a href="../ch2/ch2-07.html">
<i class="fa fa-check"></i>
<b>2.7.</b>
作用域
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="3" data-path="ch3/ch3.html">
<a href="../ch3/ch3.html">
<i class="fa fa-check"></i>
<b>3.</b>
基礎數據類型
</a>
<ul class="articles">
<li class="chapter " data-level="3.1" data-path="ch3/ch3-01.html">
<a href="../ch3/ch3-01.html">
<i class="fa fa-check"></i>
<b>3.1.</b>
整型
</a>
</li>
<li class="chapter " data-level="3.2" data-path="ch3/ch3-02.html">
<a href="../ch3/ch3-02.html">
<i class="fa fa-check"></i>
<b>3.2.</b>
浮點數
</a>
</li>
<li class="chapter " data-level="3.3" data-path="ch3/ch3-03.html">
<a href="../ch3/ch3-03.html">
<i class="fa fa-check"></i>
<b>3.3.</b>
復數
</a>
</li>
<li class="chapter " data-level="3.4" data-path="ch3/ch3-04.html">
<a href="../ch3/ch3-04.html">
<i class="fa fa-check"></i>
<b>3.4.</b>
佈爾型
</a>
</li>
<li class="chapter " data-level="3.5" data-path="ch3/ch3-05.html">
<a href="../ch3/ch3-05.html">
<i class="fa fa-check"></i>
<b>3.5.</b>
字符串
</a>
</li>
<li class="chapter " data-level="3.6" data-path="ch3/ch3-06.html">
<a href="../ch3/ch3-06.html">
<i class="fa fa-check"></i>
<b>3.6.</b>
常量
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4" data-path="ch4/ch4.html">
<a href="../ch4/ch4.html">
<i class="fa fa-check"></i>
<b>4.</b>
復閤數據類型
</a>
<ul class="articles">
<li class="chapter " data-level="4.1" data-path="ch4/ch4-01.html">
<a href="../ch4/ch4-01.html">
<i class="fa fa-check"></i>
<b>4.1.</b>
數組
</a>
</li>
<li class="chapter " data-level="4.2" data-path="ch4/ch4-02.html">
<a href="../ch4/ch4-02.html">
<i class="fa fa-check"></i>
<b>4.2.</b>
切片
</a>
</li>
<li class="chapter " data-level="4.3" data-path="ch4/ch4-03.html">
<a href="../ch4/ch4-03.html">
<i class="fa fa-check"></i>
<b>4.3.</b>
字典
</a>
</li>
<li class="chapter " data-level="4.4" data-path="ch4/ch4-04.html">
<a href="../ch4/ch4-04.html">
<i class="fa fa-check"></i>
<b>4.4.</b>
結構體
</a>
</li>
<li class="chapter " data-level="4.5" data-path="ch4/ch4-05.html">
<a href="../ch4/ch4-05.html">
<i class="fa fa-check"></i>
<b>4.5.</b>
JSON
</a>
</li>
<li class="chapter " data-level="4.6" data-path="ch4/ch4-06.html">
<a href="../ch4/ch4-06.html">
<i class="fa fa-check"></i>
<b>4.6.</b>
文本和HTML模闆
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5" data-path="ch5/ch5.html">
<a href="../ch5/ch5.html">
<i class="fa fa-check"></i>
<b>5.</b>
函數
</a>
<ul class="articles">
<li class="chapter " data-level="5.1" data-path="ch5/ch5-01.html">
<a href="../ch5/ch5-01.html">
<i class="fa fa-check"></i>
<b>5.1.</b>
函數聲明
</a>
</li>
<li class="chapter " data-level="5.2" data-path="ch5/ch5-02.html">
<a href="../ch5/ch5-02.html">
<i class="fa fa-check"></i>
<b>5.2.</b>
遞歸
</a>
</li>
<li class="chapter " data-level="5.3" data-path="ch5/ch5-03.html">
<a href="../ch5/ch5-03.html">
<i class="fa fa-check"></i>
<b>5.3.</b>
多返迴值
</a>
</li>
<li class="chapter " data-level="5.4" data-path="ch5/ch5-04.html">
<a href="../ch5/ch5-04.html">
<i class="fa fa-check"></i>
<b>5.4.</b>
錯誤
</a>
</li>
<li class="chapter " data-level="5.5" data-path="ch5/ch5-05.html">
<a href="../ch5/ch5-05.html">
<i class="fa fa-check"></i>
<b>5.5.</b>
函數值
</a>
</li>
<li class="chapter " data-level="5.6" data-path="ch5/ch5-06.html">
<a href="../ch5/ch5-06.html">
<i class="fa fa-check"></i>
<b>5.6.</b>
匿名函數
</a>
</li>
<li class="chapter " data-level="5.7" data-path="ch5/ch5-07.html">
<a href="../ch5/ch5-07.html">
<i class="fa fa-check"></i>
<b>5.7.</b>
可變參數
</a>
</li>
<li class="chapter " data-level="5.8" data-path="ch5/ch5-08.html">
<a href="../ch5/ch5-08.html">
<i class="fa fa-check"></i>
<b>5.8.</b>
Deferred函數
</a>
</li>
<li class="chapter " data-level="5.9" data-path="ch5/ch5-09.html">
<a href="../ch5/ch5-09.html">
<i class="fa fa-check"></i>
<b>5.9.</b>
Panic異常
</a>
</li>
<li class="chapter " data-level="5.10" data-path="ch5/ch5-10.html">
<a href="../ch5/ch5-10.html">
<i class="fa fa-check"></i>
<b>5.10.</b>
Recover捕穫異常
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="6" data-path="ch6/ch6.html">
<a href="../ch6/ch6.html">
<i class="fa fa-check"></i>
<b>6.</b>
方法
</a>
<ul class="articles">
<li class="chapter " data-level="6.1" data-path="ch6/ch6-01.html">
<a href="../ch6/ch6-01.html">
<i class="fa fa-check"></i>
<b>6.1.</b>
方法聲明
</a>
</li>
<li class="chapter " data-level="6.2" data-path="ch6/ch6-02.html">
<a href="../ch6/ch6-02.html">
<i class="fa fa-check"></i>
<b>6.2.</b>
基於指鍼對象的方法
</a>
</li>
<li class="chapter " data-level="6.3" data-path="ch6/ch6-03.html">
<a href="../ch6/ch6-03.html">
<i class="fa fa-check"></i>
<b>6.3.</b>
通過嵌入結構體來擴展類型
</a>
</li>
<li class="chapter " data-level="6.4" data-path="ch6/ch6-04.html">
<a href="../ch6/ch6-04.html">
<i class="fa fa-check"></i>
<b>6.4.</b>
方法值和方法錶達式
</a>
</li>
<li class="chapter " data-level="6.5" data-path="ch6/ch6-05.html">
<a href="../ch6/ch6-05.html">
<i class="fa fa-check"></i>
<b>6.5.</b>
示例: Bit數組
</a>
</li>
<li class="chapter " data-level="6.6" data-path="ch6/ch6-06.html">
<a href="../ch6/ch6-06.html">
<i class="fa fa-check"></i>
<b>6.6.</b>
封裝
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="7" data-path="ch7/ch7.html">
<a href="../ch7/ch7.html">
<i class="fa fa-check"></i>
<b>7.</b>
接口
</a>
<ul class="articles">
<li class="chapter " data-level="7.1" data-path="ch7/ch7-01.html">
<a href="../ch7/ch7-01.html">
<i class="fa fa-check"></i>
<b>7.1.</b>
接口是閤約
</a>
</li>
<li class="chapter " data-level="7.2" data-path="ch7/ch7-02.html">
<a href="../ch7/ch7-02.html">
<i class="fa fa-check"></i>
<b>7.2.</b>
接口類型
</a>
</li>
<li class="chapter " data-level="7.3" data-path="ch7/ch7-03.html">
<a href="../ch7/ch7-03.html">
<i class="fa fa-check"></i>
<b>7.3.</b>
實現接口的條件
</a>
</li>
<li class="chapter " data-level="7.4" data-path="ch7/ch7-04.html">
<a href="../ch7/ch7-04.html">
<i class="fa fa-check"></i>
<b>7.4.</b>
flag.Value接口
</a>
</li>
<li class="chapter " data-level="7.5" data-path="ch7/ch7-05.html">
<a href="../ch7/ch7-05.html">
<i class="fa fa-check"></i>
<b>7.5.</b>
接口值
</a>
</li>
<li class="chapter " data-level="7.6" data-path="ch7/ch7-06.html">
<a href="../ch7/ch7-06.html">
<i class="fa fa-check"></i>
<b>7.6.</b>
sort.Interface接口
</a>
</li>
<li class="chapter " data-level="7.7" data-path="ch7/ch7-07.html">
<a href="../ch7/ch7-07.html">
<i class="fa fa-check"></i>
<b>7.7.</b>
http.Handler接口
</a>
</li>
<li class="chapter " data-level="7.8" data-path="ch7/ch7-08.html">
<a href="../ch7/ch7-08.html">
<i class="fa fa-check"></i>
<b>7.8.</b>
error接口
</a>
</li>
<li class="chapter " data-level="7.9" data-path="ch7/ch7-09.html">
<a href="../ch7/ch7-09.html">
<i class="fa fa-check"></i>
<b>7.9.</b>
示例: 錶達式求值
</a>
</li>
<li class="chapter " data-level="7.10" data-path="ch7/ch7-10.html">
<a href="../ch7/ch7-10.html">
<i class="fa fa-check"></i>
<b>7.10.</b>
類型斷言
</a>
</li>
<li class="chapter " data-level="7.11" data-path="ch7/ch7-11.html">
<a href="../ch7/ch7-11.html">
<i class="fa fa-check"></i>
<b>7.11.</b>
基於類型斷言識彆錯誤類型
</a>
</li>
<li class="chapter " data-level="7.12" data-path="ch7/ch7-12.html">
<a href="../ch7/ch7-12.html">
<i class="fa fa-check"></i>
<b>7.12.</b>
通過類型斷言査詢接口
</a>
</li>
<li class="chapter " data-level="7.13" data-path="ch7/ch7-13.html">
<a href="../ch7/ch7-13.html">
<i class="fa fa-check"></i>
<b>7.13.</b>
類型分支
</a>
</li>
<li class="chapter " data-level="7.14" data-path="ch7/ch7-14.html">
<a href="../ch7/ch7-14.html">
<i class="fa fa-check"></i>
<b>7.14.</b>
示例: 基於標記的XML解碼
</a>
</li>
<li class="chapter " data-level="7.15" data-path="ch7/ch7-15.html">
<a href="../ch7/ch7-15.html">
<i class="fa fa-check"></i>
<b>7.15.</b>
補充幾點
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="8" data-path="ch8/ch8.html">
<a href="../ch8/ch8.html">
<i class="fa fa-check"></i>
<b>8.</b>
Goroutines和Channels
</a>
<ul class="articles">
<li class="chapter " data-level="8.1" data-path="ch8/ch8-01.html">
<a href="../ch8/ch8-01.html">
<i class="fa fa-check"></i>
<b>8.1.</b>
Goroutines
</a>
</li>
<li class="chapter " data-level="8.2" data-path="ch8/ch8-02.html">
<a href="../ch8/ch8-02.html">
<i class="fa fa-check"></i>
<b>8.2.</b>
示例: 併髮的Clock服務
</a>
</li>
<li class="chapter " data-level="8.3" data-path="ch8/ch8-03.html">
<a href="../ch8/ch8-03.html">
<i class="fa fa-check"></i>
<b>8.3.</b>
示例: 併髮的Echo服務
</a>
</li>
<li class="chapter " data-level="8.4" data-path="ch8/ch8-04.html">
<a href="../ch8/ch8-04.html">
<i class="fa fa-check"></i>
<b>8.4.</b>
Channels
</a>
</li>
<li class="chapter " data-level="8.5" data-path="ch8/ch8-05.html">
<a href="../ch8/ch8-05.html">
<i class="fa fa-check"></i>
<b>8.5.</b>
併行的循環
</a>
</li>
<li class="chapter " data-level="8.6" data-path="ch8/ch8-06.html">
<a href="../ch8/ch8-06.html">
<i class="fa fa-check"></i>
<b>8.6.</b>
示例: 併髮的Web爬蟲
</a>
</li>
<li class="chapter " data-level="8.7" data-path="ch8/ch8-07.html">
<a href="../ch8/ch8-07.html">
<i class="fa fa-check"></i>
<b>8.7.</b>
基於select的多路復用
</a>
</li>
<li class="chapter " data-level="8.8" data-path="ch8/ch8-08.html">
<a href="../ch8/ch8-08.html">
<i class="fa fa-check"></i>
<b>8.8.</b>
示例: 併髮的字典遍歷
</a>
</li>
<li class="chapter " data-level="8.9" data-path="ch8/ch8-09.html">
<a href="../ch8/ch8-09.html">
<i class="fa fa-check"></i>
<b>8.9.</b>
併髮的退齣
</a>
</li>
<li class="chapter " data-level="8.10" data-path="ch8/ch8-10.html">
<a href="../ch8/ch8-10.html">
<i class="fa fa-check"></i>
<b>8.10.</b>
示例: 聊天服務
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="9" data-path="ch9/ch9.html">
<a href="../ch9/ch9.html">
<i class="fa fa-check"></i>
<b>9.</b>
基於共享變量的併髮
</a>
<ul class="articles">
<li class="chapter " data-level="9.1" data-path="ch9/ch9-01.html">
<a href="../ch9/ch9-01.html">
<i class="fa fa-check"></i>
<b>9.1.</b>
競爭條件
</a>
</li>
<li class="chapter " data-level="9.2" data-path="ch9/ch9-02.html">
<a href="../ch9/ch9-02.html">
<i class="fa fa-check"></i>
<b>9.2.</b>
sync.Mutex互斥鎖
</a>
</li>
<li class="chapter " data-level="9.3" data-path="ch9/ch9-03.html">
<a href="../ch9/ch9-03.html">
<i class="fa fa-check"></i>
<b>9.3.</b>
sync.RWMutex讀寫鎖
</a>
</li>
<li class="chapter " data-level="9.4" data-path="ch9/ch9-04.html">
<a href="../ch9/ch9-04.html">
<i class="fa fa-check"></i>
<b>9.4.</b>
內存衕步
</a>
</li>
<li class="chapter " data-level="9.5" data-path="ch9/ch9-05.html">
<a href="../ch9/ch9-05.html">
<i class="fa fa-check"></i>
<b>9.5.</b>
sync.Once初始化
</a>
</li>
<li class="chapter " data-level="9.6" data-path="ch9/ch9-06.html">
<a href="../ch9/ch9-06.html">
<i class="fa fa-check"></i>
<b>9.6.</b>
競爭條件檢測
</a>
</li>
<li class="chapter " data-level="9.7" data-path="ch9/ch9-07.html">
<a href="../ch9/ch9-07.html">
<i class="fa fa-check"></i>
<b>9.7.</b>
示例: 併髮的非阻塞緩存
</a>
</li>
<li class="chapter " data-level="9.8" data-path="ch9/ch9-08.html">
<a href="../ch9/ch9-08.html">
<i class="fa fa-check"></i>
<b>9.8.</b>
Goroutines和綫程
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="10" data-path="ch10/ch10.html">
<a href="../ch10/ch10.html">
<i class="fa fa-check"></i>
<b>10.</b>
包和工具
</a>
<ul class="articles">
<li class="chapter " data-level="10.1" data-path="ch10/ch10-01.html">
<a href="../ch10/ch10-01.html">
<i class="fa fa-check"></i>
<b>10.1.</b>
簡介
</a>
</li>
<li class="chapter " data-level="10.2" data-path="ch10/ch10-02.html">
<a href="../ch10/ch10-02.html">
<i class="fa fa-check"></i>
<b>10.2.</b>
導入路徑
</a>
</li>
<li class="chapter " data-level="10.3" data-path="ch10/ch10-03.html">
<a href="../ch10/ch10-03.html">
<i class="fa fa-check"></i>
<b>10.3.</b>
包聲明
</a>
</li>
<li class="chapter " data-level="10.4" data-path="ch10/ch10-04.html">
<a href="../ch10/ch10-04.html">
<i class="fa fa-check"></i>
<b>10.4.</b>
導入聲明
</a>
</li>
<li class="chapter " data-level="10.5" data-path="ch10/ch10-05.html">
<a href="../ch10/ch10-05.html">
<i class="fa fa-check"></i>
<b>10.5.</b>
匿名導入
</a>
</li>
<li class="chapter " data-level="10.6" data-path="ch10/ch10-06.html">
<a href="../ch10/ch10-06.html">
<i class="fa fa-check"></i>
<b>10.6.</b>
包和命名
</a>
</li>
<li class="chapter " data-level="10.7" data-path="ch10/ch10-07.html">
<a href="../ch10/ch10-07.html">
<i class="fa fa-check"></i>
<b>10.7.</b>
工具
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="11" data-path="ch11/ch11.html">
<a href="../ch11/ch11.html">
<i class="fa fa-check"></i>
<b>11.</b>
測試
</a>
<ul class="articles">
<li class="chapter " data-level="11.1" data-path="ch11/ch11-01.html">
<a href="../ch11/ch11-01.html">
<i class="fa fa-check"></i>
<b>11.1.</b>
go test
</a>
</li>
<li class="chapter " data-level="11.2" data-path="ch11/ch11-02.html">
<a href="../ch11/ch11-02.html">
<i class="fa fa-check"></i>
<b>11.2.</b>
測試函數
</a>
</li>
<li class="chapter " data-level="11.3" data-path="ch11/ch11-03.html">
<a href="../ch11/ch11-03.html">
<i class="fa fa-check"></i>
<b>11.3.</b>
測試覆蓋率
</a>
</li>
<li class="chapter " data-level="11.4" data-path="ch11/ch11-04.html">
<a href="../ch11/ch11-04.html">
<i class="fa fa-check"></i>
<b>11.4.</b>
基準測試
</a>
</li>
<li class="chapter " data-level="11.5" data-path="ch11/ch11-05.html">
<a href="../ch11/ch11-05.html">
<i class="fa fa-check"></i>
<b>11.5.</b>
剖析
</a>
</li>
<li class="chapter " data-level="11.6" data-path="ch11/ch11-06.html">
<a href="../ch11/ch11-06.html">
<i class="fa fa-check"></i>
<b>11.6.</b>
示例函數
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="12" data-path="ch12/ch12.html">
<a href="../ch12/ch12.html">
<i class="fa fa-check"></i>
<b>12.</b>
反射
</a>
<ul class="articles">
<li class="chapter " data-level="12.1" data-path="ch12/ch12-01.html">
<a href="../ch12/ch12-01.html">
<i class="fa fa-check"></i>
<b>12.1.</b>
為何需要反射?
</a>
</li>
<li class="chapter " data-level="12.2" data-path="ch12/ch12-02.html">
<a href="../ch12/ch12-02.html">
<i class="fa fa-check"></i>
<b>12.2.</b>
reflect.Type和reflect.Value
</a>
</li>
<li class="chapter " data-level="12.3" data-path="ch12/ch12-03.html">
<a href="../ch12/ch12-03.html">
<i class="fa fa-check"></i>
<b>12.3.</b>
Display遞歸打印
</a>
</li>
<li class="chapter " data-level="12.4" data-path="ch12/ch12-04.html">
<a href="../ch12/ch12-04.html">
<i class="fa fa-check"></i>
<b>12.4.</b>
示例: 編碼S錶達式
</a>
</li>
<li class="chapter " data-level="12.5" data-path="ch12/ch12-05.html">
<a href="../ch12/ch12-05.html">
<i class="fa fa-check"></i>
<b>12.5.</b>
通過reflect.Value脩改值
</a>
</li>
<li class="chapter " data-level="12.6" data-path="ch12/ch12-06.html">
<a href="../ch12/ch12-06.html">
<i class="fa fa-check"></i>
<b>12.6.</b>
示例: 解碼S錶達式
</a>
</li>
<li class="chapter " data-level="12.7" data-path="ch12/ch12-07.html">
<a href="../ch12/ch12-07.html">
<i class="fa fa-check"></i>
<b>12.7.</b>
穫取結構體字段標識
</a>
</li>
<li class="chapter " data-level="12.8" data-path="ch12/ch12-08.html">
<a href="../ch12/ch12-08.html">
<i class="fa fa-check"></i>
<b>12.8.</b>
顯示一個類型的方法集
</a>
</li>
<li class="chapter " data-level="12.9" data-path="ch12/ch12-09.html">
<a href="../ch12/ch12-09.html">
<i class="fa fa-check"></i>
<b>12.9.</b>
幾點忠告
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="13" data-path="ch13/ch13.html">
<a href="../ch13/ch13.html">
<i class="fa fa-check"></i>
<b>13.</b>
底層編程
</a>
<ul class="articles">
<li class="chapter " data-level="13.1" data-path="ch13/ch13-01.html">
<a href="../ch13/ch13-01.html">
<i class="fa fa-check"></i>
<b>13.1.</b>
unsafe.Sizeof, Alignof 和 Offsetof
</a>
</li>
<li class="chapter " data-level="13.2" data-path="ch13/ch13-02.html">
<a href="../ch13/ch13-02.html">
<i class="fa fa-check"></i>
<b>13.2.</b>
unsafe.Pointer
</a>
</li>
<li class="chapter " data-level="13.3" data-path="ch13/ch13-03.html">
<a href="../ch13/ch13-03.html">
<i class="fa fa-check"></i>
<b>13.3.</b>
示例: 深度相等判斷
</a>
</li>
<li class="chapter " data-level="13.4" data-path="ch13/ch13-04.html">
<a href="../ch13/ch13-04.html">
<i class="fa fa-check"></i>
<b>13.4.</b>
通過cgo調用C代碼
</a>
</li>
<li class="chapter " data-level="13.5" data-path="ch13/ch13-05.html">
<a href="../ch13/ch13-05.html">
<i class="fa fa-check"></i>
<b>13.5.</b>
幾點忠告
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="14" data-path="exercise/ex.html">
<a href="../exercise/ex.html">
<i class="fa fa-check"></i>
<b>14.</b>
習題解答
</a>
<ul class="articles">
<li class="chapter " data-level="14.1" data-path="exercise/ex-ch1.html">
<a href="../exercise/ex-ch1.html">
<i class="fa fa-check"></i>
<b>14.1.</b>
第一章 入門
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="15" data-path="errata.html">
<a href="../errata.html">
<i class="fa fa-check"></i>
<b>15.</b>
勘誤
</a>
</li>
<li class="divider"></li>
<li>
<a href="https://www.gitbook.com" target="blank" class="gitbook-link">
本書使用 GitBook 釋出
</a>
</li>
</ul>
</nav>
</div>
<div class="book-body">
<div class="body-inner">
<div class="book-header" role="navigation">
<!-- Actions Left -->
<!-- Title -->
<h1>
<i class="fa fa-circle-o-notch fa-spin"></i>
<a href="../" >Go编程语言</a>
</h1>
</div>
<div class="page-wrapper" tabindex="-1" role="main">
<div class="page-inner">
<section class="normal" id="section-">
<h2 id="24-&#x8CE6;&#x503C;">2.4. &#x8CE6;&#x503C;</h2>
<p>&#x4F7F;&#x7528;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x53EF;&#x4EE5;&#x66F4;&#x65B0;&#x4E00;&#x500B;&#x8B8A;&#x91CF;&#x7684;&#x503C;, &#x6700;&#x7C21;&#x55AE;&#x7684;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x662F;&#x5C07;&#x8981;&#x88AB;&#x8CE6;&#x503C;&#x7684;&#x8B8A;&#x91CF;&#x653E;&#x5728; <code>=</code> &#x7684;&#x5DE6;&#x908A;, &#x65B0;&#x503C;&#x7684;&#x9336;&#x9054;&#x5F0F;&#x653E;&#x5728; <code>=</code> &#x53F3;&#x908A;.</p>
<pre><code class="lang-Go">x = <span class="hljs-number">1</span> <span class="hljs-comment">// &#x547D;&#x4EE4;&#x8B8A;&#x91CF;&#x7684;&#x8CE6;&#x503C;</span>
*p = <span class="hljs-constant">true</span> <span class="hljs-comment">// &#x901A;&#x904E;&#x6307;&#x937C;&#x9593;&#x63A5;&#x8CE6;&#x503C;</span>
person.name = <span class="hljs-string">&quot;bob&quot;</span> <span class="hljs-comment">// &#x7D50;&#x69CB;&#x9AD4;&#x5B57;&#x6BB5;&#x8CE6;&#x503C;</span>
count[x] = count[x] * scale <span class="hljs-comment">// &#x6578;&#x7D44;, &#x5207;&#x7247; &#x6216; &#x5B57;&#x5178;&#x7684; &#x5143;&#x7D20;&#x8CE6;&#x503C;</span>
</code></pre>
<p>&#x7279;&#x5B9A;&#x7684;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x548C;&#x4E8C;&#x5143;&#x7B97;&#x672E;&#x5FA9;&#x95A4;&#x64CD;&#x4F5C;&#x6709;&#x4E00;&#x500B;&#x7C21;&#x6F54;&#x5F62;&#x5F0F;, &#x4F8B;&#x5982;&#x4E0A;&#x9EAB;&#x6700;&#x5F8C;&#x7684;&#x8A9E;&#x53E5;&#x53EF;&#x4EE5;&#x91CD;&#x5BEB;&#x70BA;:</p>
<pre><code class="lang-Go">count[x] *= scale
</code></pre>
<p>&#x9019;&#x6A23;&#x53EF;&#x4EE5;&#x7701;&#x53BB;&#x5C0D;&#x8B8A;&#x91CF;&#x9336;&#x9054;&#x5F0F;&#x7684;&#x91CD;&#x5FA9;&#x8A08;&#x7B97;.</p>
<p>&#x6578;&#x503C;&#x8B8A;&#x91CF;&#x4E5F;&#x53EF;&#x4EE5;&#x652F;&#x6301; <code>++</code> &#x905E;&#x589E;&#x548C; <code>--</code> &#x905E;&#x6E1B;&#x8A9E;&#x53E5;:</p>
<pre><code class="lang-Go">v := <span class="hljs-number">1</span>
v++ <span class="hljs-comment">// &#x7B49;&#x50F9;&#x65B9;&#x5F0F; v = v + 1; v &#x8B8A;&#x6210; 2 </span>
v-- <span class="hljs-comment">// &#x7B49;&#x50F9;&#x65B9;&#x5F0F; v = v - 1; v &#x8B8A;&#x6210; 1</span>
</code></pre>
<h3 id="241-&#x5143;&#x7D44;&#x8CE6;&#x503C;">2.4.1. &#x5143;&#x7D44;&#x8CE6;&#x503C;</h3>
<p>&#x5143;&#x7D44;&#x8CE6;&#x503C;&#x662F;&#x53E6;&#x4E00;&#x7A2E;&#x5F62;&#x5F0F;&#x7684;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;, &#x5141;&#x8A31;&#x8855;&#x6642;&#x66F4;&#x65B0;&#x591A;&#x500B;&#x8B8A;&#x91CF;&#x7684;&#x503C;. &#x5728;&#x8CE6;&#x503C;&#x4E4B;&#x524D;, &#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x53F3;&#x908A;&#x7684;&#x6240;&#x6709;&#x9336;&#x9054;&#x5F0F;&#x5C07;&#x6703;&#x5148;&#x9032;&#x884C;&#x6C42;&#x503C;, &#x7136;&#x5F8C;&#x518D;&#x7D71;&#x4E00;&#x66F4;&#x65B0;&#x5DE6;&#x908A;&#x8B8A;&#x91CF;&#x7684;&#x503C;. &#x9019;&#x5C0D;&#x65BC;&#x8655;&#x7406;&#x6709;&#x4E9B;&#x8855;&#x6642;&#x9F63;&#x73FE;&#x5728;&#x5143;&#x7D44;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x5DE6;&#x53F3;&#x5169;&#x908A;&#x7684;&#x8B8A;&#x91CF;&#x5F88;&#x6709;&#x5E6B;&#x52A9;, &#x4F8B;&#x5982;&#x6211;&#x5011;&#x53EF;&#x4EE5;&#x9019;&#x6A23;&#x4EA4;&#x63DB;&#x5169;&#x500B;&#x8B8A;&#x91CF;&#x7684;&#x503C;:</p>
<pre><code class="lang-Go">x, y = y, x
a[i], a[j] = a[j], a[i]
</code></pre>
<p>&#x6216;&#x8005;&#x662F;&#x8A08;&#x7B97;&#x5169;&#x500B;&#x6574;&#x6578;&#x503C;&#x7684;&#x7684;&#x6700;&#x5927;&#x516C;&#x7D04;&#x6578;(GCD):</p>
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> gcd(x, y <span class="hljs-typename">int</span>) <span class="hljs-typename">int</span> {
<span class="hljs-keyword">for</span> y != <span class="hljs-number">0</span> {
x, y = y, x%y
}
<span class="hljs-keyword">return</span> x
}
</code></pre>
<p>&#x6216;&#x8005;&#x662F;&#x8A08;&#x7B97;&#x6590;&#x6CE2;&#x7D0D;&#x5951;&#x6578;&#x5217;(Fibonacci)&#x7684;&#x7B2C;N&#x500B;&#x6578;:</p>
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> fib(n <span class="hljs-typename">int</span>) <span class="hljs-typename">int</span> {
x, y := <span class="hljs-number">0</span>, <span class="hljs-number">1</span>
<span class="hljs-keyword">for</span> i := <span class="hljs-number">0</span>; i &lt; n; i++ {
x, y = y, x+y
}
<span class="hljs-keyword">return</span> x
}
</code></pre>
<p>&#x5143;&#x7D44;&#x8CE6;&#x503C;&#x4E5F;&#x53EF;&#x4EE5;&#x4F7F;&#x4E00;&#x7E6B;&#x5217;&#x7463;&#x788E;&#x8CE6;&#x503C;&#x66F4;&#x7DCA;&#x6E4A;(&#x8B6F;&#x8A3B;: &#x7279;&#x5F46;&#x662F;&#x5728;for&#x5FAA;&#x74B0;&#x7684;&#x521D;&#x59CB;&#x5316;&#x90E8;&#x5206;),</p>
<pre><code class="lang-Go">i, j, k = <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">5</span>
</code></pre>
<p>&#x4F46;&#x5982;&#x679C;&#x9336;&#x9054;&#x5F0F;&#x592A;&#x5FA9;&#x96DC;&#x7684;&#x8A71;, &#x61C9;&#x8A72;&#x76E1;&#x91CF;&#x907F;&#x514D;&#x5143;&#x7D44;&#x8CE6;&#x503C;; &#x56E0;&#x70BA;&#x4E00;&#x500B;&#x500B;&#x55AE;&#x7368;&#x7684;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x7684;&#x53EF;&#x8B80;&#x6027;&#x6703;&#x66F4;&#x597D;.</p>
<p>&#x67D0;&#x4E9B;&#x9336;&#x9054;&#x5F0F;&#x6703;&#x7522;&#x751F;&#x591A;&#x500B;&#x503C;, &#x6BD4;&#x5982;&#x8ABF;&#x7528;&#x4E00;&#x500B;&#x6709;&#x591A;&#x500B;&#x8FD4;&#x8FF4;&#x503C;&#x7684;&#x51FD;&#x6578;.
&#x7576;&#x9019;&#x6A23;&#x4E00;&#x500B;&#x51FD;&#x6578;&#x8ABF;&#x7528;&#x9F63;&#x73FE;&#x5728;&#x5143;&#x7D44;&#x8CE6;&#x503C;&#x53F3;&#x908A;&#x7684;&#x9336;&#x9054;&#x5F0F;&#x4E2D;&#x6642;(&#x8B6F;&#x8A3B;: &#x53F3;&#x908A;&#x4E0D;&#x80FD;&#x518D;&#x6709;&#x5176;&#x4ED6;&#x9336;&#x9054;&#x5F0F;), &#x5DE6;&#x908A;&#x8B8A;&#x91CF;&#x7684;&#x6578;&#x76EE;&#x5FC5;&#x9B1A;&#x548C;&#x53F3;&#x908A;&#x4E00;&#x7DFB;.</p>
<pre><code class="lang-Go">f, err = os.Open(<span class="hljs-string">&quot;foo.txt&quot;</span>) <span class="hljs-comment">// function call returns two values</span>
</code></pre>
<p>&#x901A;&#x5E38;, &#x9019;&#x985E;&#x51FD;&#x6578;&#x6703;&#x7528;&#x984D;&#x5916;&#x7684;&#x8FD4;&#x8FF4;&#x503C;&#x9336;&#x9054;&#x67D0;&#x7A2E;&#x932F;&#x8AA4;&#x985E;&#x578B;, &#x4F8B;&#x5982; os.Open &#x662F;&#x8FD4;&#x8FF4;&#x4E00;&#x500B; error &#x985E;&#x578B;&#x7684;&#x932F;&#x8AA4;, &#x9084;&#x6709;&#x4E00;&#x4E9B;&#x662F;&#x8FD4;&#x8FF4;&#x4F48;&#x723E;&#x503C;, &#x901A;&#x5E38;&#x88AB;&#x7A31;&#x70BA;ok. &#x5728;&#x7A0D;&#x5F8C;&#x6211;&#x5011;&#x770B;&#x5230;&#x7684;&#x4E09;&#x500B;&#x64CD;&#x4F5C;&#x90FD;&#x662F;&#x985E;&#x4F3C;&#x7684;&#x884C;&#x70BA;. &#x5982;&#x679C; &#x5B57;&#x5178;&#x67FB;&#x627E;(&#xA7;4.3), &#x985E;&#x578B;&#x65B7;&#x8A00;(&#xA7;7.10), &#x6216; &#x901A;&#x9053;&#x63A5;&#x6536;(&#xA7;8.4.2) &#x9F63;&#x73FE;&#x5728;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x7684;&#x53F3;&#x908A;, &#x5B83;&#x5011;&#x90FD;&#x5C07;&#x7522;&#x751F;&#x5169;&#x500B;&#x7D50;&#x679C;, &#x6709;&#x4E00;&#x500B;&#x984D;&#x5916;&#x7684;&#x4F48;&#x723E;&#x7D50;&#x679C;&#x9336;&#x793A;&#x64CD;&#x4F5C;&#x662F;&#x5426;&#x6210;&#x529F;:</p>
<pre><code class="lang-Go">v, ok = m[key] <span class="hljs-comment">// map lookup</span>
v, ok = x.(T) <span class="hljs-comment">// type assertion</span>
v, ok = &lt;-ch <span class="hljs-comment">// channel receive</span>
</code></pre>
<p>&#x548C;&#x8B8A;&#x91CF;&#x7684;&#x8072;&#x660E;&#x4E00;&#x6A23;, &#x6211;&#x5011;&#x53EF;&#x4EE5;&#x7528;&#x4E0B;&#x5283;&#x7DAB;&#x7A7A;&#x767D;&#x6A19;&#x8B58;&#x7B26; <code>_</code> &#x4F86;&#x4E1F;&#x68C4;&#x4E0D;&#x9700;&#x8981;&#x7684;&#x503C;.</p>
<pre><code class="lang-Go">_, err = io.Copy(dst, src) <span class="hljs-comment">// &#x4E1F;&#x68C4;&#x5B57;&#x7BC0;&#x6578;</span>
_, ok = x.(T) <span class="hljs-comment">// &#x96BB;&#x6AA2;&#x6E2C;&#x985E;&#x578B;, &#x5FFD;&#x7565;&#x5177;&#x9AD4;&#x503C;</span>
</code></pre>
<h3 id="242-&#x53EF;&#x8CE6;&#x503C;&#x6027;">2.4.2. &#x53EF;&#x8CE6;&#x503C;&#x6027;</h3>
<p>&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x662F;&#x986F;&#x793A;&#x7684;&#x8CE6;&#x503C;&#x5F62;&#x5F0F;, &#x4F46;&#x662F;&#x7A0B;&#x5E8F;&#x4E2D;&#x9084;&#x6709;&#x5F88;&#x591A;&#x5730;&#x65B9;&#x6703;&#x9AEE;&#x9001;&#x96B1;&#x5F0F;&#x7684;&#x8CE6;&#x503C;&#x884C;&#x70BA;: &#x51FD;&#x6578;&#x8ABF;&#x7528;&#x5C07;&#x96B1;&#x5F0F;&#x5730;&#x5C07;&#x8ABF;&#x7528;&#x53C3;&#x6578;&#x7684;&#x503C;&#x8CE6;&#x503C;&#x7D66;&#x51FD;&#x6578;&#x7684;&#x53C3;&#x6578;&#x8B8A;&#x91CF;, &#x4E00;&#x500B;&#x8FD4;&#x8FF4;&#x8A9E;&#x53E5;&#x5C07;&#x96B1;&#x5F0F;&#x5730;&#x5C07;&#x8FD4;&#x8FF4;&#x64CD;&#x4F5C;&#x7684;&#x503C;&#x8CE6;&#x503C;&#x7D66;&#x7D50;&#x679C;&#x8B8A;&#x91CF;, &#x4E00;&#x500B;&#x5FA9;&#x95A4;&#x985E;&#x578B;&#x7684;&#x5B57;&#x9EAB;&#x91CF;(&#xA7;4.2)&#x4E5F;&#x6703;&#x7522;&#x751F;&#x8CE6;&#x503C;&#x884C;&#x70BA;. &#x4F8B;&#x5982;&#x4E0B;&#x9EAB;&#x7684;&#x8A9E;&#x53E5;:</p>
<pre><code class="lang-Go">medals := []<span class="hljs-typename">string</span>{<span class="hljs-string">&quot;gold&quot;</span>, <span class="hljs-string">&quot;silver&quot;</span>, <span class="hljs-string">&quot;bronze&quot;</span>}
</code></pre>
<p>&#x96B1;&#x5F0F;&#x5730;&#x5C0D;&#x5207;&#x7247;&#x7684;&#x6BCF;&#x500B;&#x5143;&#x7D20;&#x9032;&#x884C;&#x8CE6;&#x503C;&#x64CD;&#x4F5C;, &#x985E;&#x4F3C;&#x9019;&#x6A23;&#x5BEB;&#x7684;&#x884C;&#x70BA;:</p>
<pre><code class="lang-Go">medals[<span class="hljs-number">0</span>] = <span class="hljs-string">&quot;gold&quot;</span>
medals[<span class="hljs-number">1</span>] = <span class="hljs-string">&quot;silver&quot;</span>
medals[<span class="hljs-number">2</span>] = <span class="hljs-string">&quot;bronze&quot;</span>
</code></pre>
<p>&#x5B57;&#x5178;&#x548C;&#x7BA1;&#x9053;&#x7684;&#x5143;&#x7D20;, &#x96D6;&#x7136;&#x4E0D;&#x662F;&#x666E;&#x901A;&#x7684;&#x8B8A;&#x91CF;, &#x4F46;&#x662F;&#x4E5F;&#x6709;&#x985E;&#x4F3C;&#x7684;&#x96B1;&#x5F0F;&#x8CE6;&#x503C;&#x884C;&#x70BA;.</p>
<p>&#x4E0D;&#x7BA1;&#x662F;&#x96B1;&#x5F0F;&#x9084;&#x662F;&#x986F;&#x793A;&#x5730;&#x8CE6;&#x503C;, &#x5728;&#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x5750;&#x6A19;&#x7684;&#x8B8A;&#x91CF;&#x548C;&#x53F3;&#x908A;&#x6700;&#x7D42;&#x7684;&#x6C42;&#x5230;&#x7684;&#x503C;&#x5FC5;&#x9B1A;&#x6709;&#x76F8;&#x8855;&#x7684;&#x6578;&#x64DA;&#x985E;&#x578B;. &#x66F4;&#x76F4;&#x767D;&#x5730;&#x8AAA;, &#x96BB;&#x6709;&#x53F3;&#x908A;&#x7684;&#x503C;&#x5C0D;&#x65BC;&#x5DE6;&#x908A;&#x7684;&#x8B8A;&#x91CF;&#x662F;&#x53EF;&#x8CE6;&#x503C;&#x7684;, &#x8CE6;&#x503C;&#x8A9E;&#x53E5;&#x7E94;&#x662F;&#x5141;&#x8A31;&#x7684;.</p>
<p>&#x53EF;&#x8CE6;&#x503C;&#x6027;&#x7684;&#x898F;&#x5247;&#x5C0D;&#x65BC;&#x4E0D;&#x8855;&#x985E;&#x578B;&#x6709;&#x4E0D;&#x8855;&#x8981;&#x6C42;, &#x5C0D;&#x6BCF;&#x500B;&#x65B0;&#x985E;&#x578B;&#x6709;&#x95DC;&#x7684;&#x5730;&#x65B9;&#x6211;&#x5011;&#x6703;&#x5C08;&#x9580;&#x89E3;&#x91CB;.
&#x5C0D;&#x65BC;&#x76EE;&#x524D;&#x6211;&#x5011;&#x5DF2;&#x7D93;&#x8A0E;&#x8AD6;&#x904E;&#x7684;&#x985E;&#x578B;, &#x5B83;&#x7684;&#x898F;&#x5247;&#x662F;&#x7C21;&#x55AE;&#x7684;: &#x985E;&#x578B;&#x5FC5;&#x9B1A;&#x5B8C;&#x5168;&#x5339;&#x914D;, nil &#x53EF;&#x4EE5;&#x8CE6;&#x503C;&#x7D66;&#x4EFB;&#x4F55;&#x6307;&#x937C;&#x6216;&#x5F15;&#x7528;&#x985E;&#x578B;&#x7684;&#x8B8A;&#x91CF;. &#x5E38;&#x91CF;(&#xA7;3.6)&#x6709;&#x66F4;&#x9748;&#x6D3B;&#x7684;&#x898F;&#x5247;, &#x9019;&#x6A23;&#x53EF;&#x4EE5;&#x907F;&#x514D;&#x4E0D;&#x5FC5;&#x8981;&#x7684;&#x986F;&#x793A;&#x985E;&#x578B;&#x8F49;&#x63DB;.</p>
<p>&#x5C0D;&#x65BC;&#x5169;&#x500B;&#x503C;&#x662F;&#x5426;&#x53EF;&#x4EE5;&#x7528; <code>==</code> &#x6216; <code>!=</code> &#x9032;&#x884C;&#x76F8;&#x7B49;&#x6BD4;&#x8F03;&#x7684;&#x80FD;&#x529B;&#x4E5F;&#x548C;&#x53EF;&#x8CE6;&#x503C;&#x80FD;&#x529B;&#x6709;&#x95DC;&#x7E6B;:
&#x5C0D;&#x65BC;&#x4EFB;&#x4F55;&#x7684;&#x6BD4;&#x8F03;, &#x7B2C;&#x4E00;&#x500B;&#x64CD;&#x4F5C;&#x5FC5;&#x9B1A;&#x662F;&#x53EF;&#x7528;&#x65BC;&#x7B2C;&#x4E8C;&#x500B;&#x64CD;&#x4F5C;&#x985E;&#x578B;&#x7684;&#x8B8A;&#x91CF;&#x7684;&#x8CE6;&#x503C;&#x7684;, &#x53CD;&#x4E4B;&#x4F9D;&#x7136;.
&#x548C;&#x524D;&#x9EAB;&#x4E00;&#x6A23;, &#x6211;&#x5011;&#x6703;&#x5C0D;&#x6BCF;&#x500B;&#x65B0;&#x985E;&#x578B;&#x6BD4;&#x8F03;&#x6709;&#x95DC;&#x7684;&#x5730;&#x65B9;&#x6703;&#x505A;&#x5C08;&#x9580;&#x89E3;&#x91CB;.</p>
</section>
</div>
</div>
</div>
<a href="../ch2/ch2-03.html" class="navigation navigation-prev " aria-label="Previous page: 變量"><i class="fa fa-angle-left"></i></a>
<a href="../ch2/ch2-05.html" class="navigation navigation-next " aria-label="Next page: 類型"><i class="fa fa-angle-right"></i></a>
</div>
</div>
<script src="../gitbook/app.js"></script>
<script src="../gitbook/plugins/gitbook-plugin-search/lunr.min.js"></script>
<script src="../gitbook/plugins/gitbook-plugin-search/search.js"></script>
<script src="../gitbook/plugins/gitbook-plugin-sharing/buttons.js"></script>
<script src="../gitbook/plugins/gitbook-plugin-fontsettings/buttons.js"></script>
<script>
require(["gitbook"], function(gitbook) {
var config = {"highlight":{},"search":{},"sharing":{"facebook":true,"twitter":true,"google":false,"weibo":false,"instapaper":false,"vk":false,"all":["facebook","google","twitter","weibo","instapaper"]},"fontsettings":{"theme":"white","family":"sans","size":2}};
gitbook.start(config);
});
</script>
</body>
</html>