1.7 Text Editing

1. File Content and Document Formats

1.1 Plain Text, Rich Text, and Typesetting Documents

Files are not just divided into "plain text" and "rich text" categories. The files we encounter in daily life generally come in the following three forms:

2. Character Encoding

2.1 Characters, Encoding, and Decoding

Character encoding defines the mapping between characters and byte sequences. Converting characters to bytes is called encoding, converting bytes back to characters is called decoding, and converting text from one encoding to another is called transcoding.

Correct transcoding first decodes according to the source encoding, then re-encodes according to the target encoding. For example, when converting a GBK file to UTF-8, you must first confirm that the source file really is GBK; reading GBK bytes directly as UTF-8 is not transcoding but erroneous decoding.

2.2 Comparison of Common Encodings

2.3 How Mojibake Occurs

Feeding the same byte sequence to different decoders may produce completely different text, or may cause errors because the byte sequence is invalid. The arrows in the table below indicate erroneous decoding, not correct transcoding; the results depend on the decoder's error-handling strategy, here using the common "replace undecodable bytes with U+FFFD" as an example.

When UTF-8 bytes are erroneously decoded as GBK, some byte combinations happen to map to GBK characters, so readable but meaningless Chinese characters such as 浣犲ソ often appear; invalid or unpaired bytes may still display as �. When GBK bytes are erroneously decoded as UTF-8, many byte sequences do not conform to UTF-8 rules, and the editor may report an error, refuse to open the file, or display one or more �; the result cannot be summarized as a fixed number of replacement characters.

2.4 Encoding Conventions and BOM

BOM (Byte Order Mark) is a group of special bytes written at the beginning of a file to mark the encoding. The UTF-16 BOM is used to distinguish byte order: starting with FF FE means UTF-16 LE, and starting with FE FF means UTF-16 BE. UTF-8 has no byte-order issue; its BOM (EF BB BF) only serves as an encoding signature, helping tools identify the file as UTF-8.

• Prefer UTF-8 for new projects; VS Code defaults to UTF-8 without BOM
• Whether to use a BOM depends on the file format, protocol, and toolchain requirements; UTF-8 has no byte-order issue, and the BOM only serves as an encoding signature
• Teams should make the encoding explicit through project documentation, editor configuration, or the toolchain; .editorconfig only takes effect when the repository actually adopts it and relevant tools support it
• Legacy tools, course grading systems, or historical files may require encodings such as GBK; do not convert them to UTF-8 in bulk without confirmation

3. Line Endings

3.1 Common Line Endings

There are two common line-ending sequences for text files:

Inconsistent line endings will not cause mojibake, but they may make Git treat every line as modified. If the shebang of a Shell script (see 1.12 Shell Basics) or the end of a command carries a stray \r, errors such as bad interpreter and command not found may also occur in Unix-like environments.

3.2 Handling Cross-Platform Collaboration

A project can specify line-ending rules with a .gitattributes file in the root directory. Since this file is committed with the repository, it is easier to keep consistent than configuring individually per member:

# Automatically detect text files and normalize to LF in the Git index
* text=auto
# When checking out to the working tree, Shell scripts use LF, batch files use CRLF
*.sh text eol=lf
*.bat text eol=crlf
*.cmd text eol=crlf

eol controls the line endings used when files are checked out to the working tree; files recognized as text are normalized to LF in the Git index. When the repository has no convention, the personal core.autocrlf setting participates in deciding the conversion behavior. You can check the current value before modifying global settings:

# May produce no output when not configured
git config --global --get core.autocrlf

4. VS Code: Download, Installation, and First Use

This section only covers the installation and basic use of VS Code; environment setup such as compilers will be covered in 1.14 Windows Environment Setup.

4.1 Download and Installation

Go to the VS Code download page and choose x64 or Arm64 according to the CPU architecture. Download the System Installer package.

Run the installer and read the options at each step. It is recommended to check "Add 'Open with Code' action to Windows Explorer file context menu" and "Add 'Open with Code' action to Windows Explorer directory context menu".

The installer adds the code command to PATH by default; after installation, you need to reopen the terminal before code . can open the current folder. Shortcuts and file associations can be chosen as needed.

Verify the installation: launch VS Code from the Start menu; you can also reopen the terminal and run code --version to check whether the command is available.

4.2 Install the Chinese Language Pack

Readers who are used to the English interface can skip this section. For the rest:

1. Open the "Extensions" panel in the sidebar (Ctrl + Shift + X)
2. Search for Chinese (Simplified) (简体中文) Language Pack for Visual Studio Code
3. Click "Install"; when done, click Change Language And Restart, and VS Code will restart automatically and switch to Simplified Chinese

4.3 Interface Overview and Common Entry Points

Common entry points:

• Open folder: Ctrl + K, then press Ctrl + O after releasing ("File → Open Folder")
• Integrated terminal: Ctrl + ` ("Terminal → New Terminal")
• Command palette: Ctrl + Shift + P (see below)

5. VS Code Advanced Tips

5.1 Multi-Cursor Editing

Multi-cursor lets you edit multiple places at once. The following are the default Windows keybindings; shortcuts may be overridden by GPU drivers, system tools, or custom keybindings:

For example, when you need to change several occurrences of the same text, select one and press Ctrl + D to add matches one by one; when you reach a position that should not be changed, press Ctrl + K, release, then press Ctrl + D to skip the current match. Only type the replacement after confirming all selections are correct.

5.2 Find and Replace

Clicking the .* icon in the find box enables regular expressions. For example, the following rule can match simple console.log(...) calls that are on a single line and whose arguments contain no right parenthesis, while keeping the content inside the parentheses:

Find: console\.log\(([^\r\n()]*)\)
Replace: console.debug($1)

This is not a general-purpose JavaScript transformation rule: cases such as console.log(fn()), arguments spanning multiple lines, or right parentheses inside strings may not be handled correctly. Check the preview before running a project-wide replace; when code structure is involved, use the language service, AST tools, or confirm item by item.

5.3 Regular Expressions

The advanced way of find and replace is the regular expression, which describes matching patterns with symbols and can match a whole class of text at once instead of searching character by character. The .* icon in the upper-right corner of the VS Code find box is the toggle for regular expressions.

Common metacharacters:

Key points:

• ., *, (, |, \, etc. have special meanings in regular expressions; to match the symbol itself, escape it with a preceding \ (e.g., \., \().
• ( ... ) stores the matched content in a capture group, referenced in the replacement as $1, $2, and so on. For example, to change the date format from 2024-11-15 to 2024/11/15:

Find: (\d{4})-(\d{2})-(\d{2})
Replace: $1/$2/$3

• Wildcards are not regular expressions. The *.cpp in 1.12 Shell Basics matches a whole segment of a file name, while regular expressions match any text fragment and can describe more complex patterns with \d+, (ab)+, and so on.
• Regular expression syntax is not identical across tools: VS Code uses the Rust regex engine, where . does not match newlines; grep uses "basic regular expressions (BRE)" by default, where +, (, etc. only have special meanings when written as \+, \(. Check the syntax documentation of a tool before using it.

5.4 Code Snippets

Code blocks you type repeatedly can be turned into snippets: type a few letters and press Tab to expand automatically. In VS Code: Ctrl + Shift + P → Configure User Snippets → choose a language.

For example, create a quick output snippet for C++:

{
  // Quickly insert a cout statement
  "Print": {
    "prefix": "cout",
    "body": ["std::cout << ${1:content} << std::endl;"],
    "description": "Quickly insert a cout statement"
  }
}

After that, type cout and press Tab, and it expands automatically, placing the cursor at ${1:content} waiting for your input.

5.5 Command Palette

Ctrl + Shift + P opens the command palette. It lists all commands registered in the current environment, which is convenient for finding settings entries and actions by keyword without memorizing every menu level.

5.6 Quick Overview of Other Common Shortcuts

The following actions can be invoked with default shortcuts or the command palette:

Common settings can apply only to the current user or be shared with the project.

6. Editor Configuration and Sync

6.1 JSON Configuration Files

VS Code provides both a graphical settings UI and JSON configuration files. JSON is suitable for precise editing, reviewing diffs, and sharing workspace configuration:

• User settings: Ctrl + Shift + P → Preferences: Open User Settings (JSON)
• Workspace settings: the project's .vscode/settings.json, which only applies to the current project

Common configuration examples:

{
  // Font size
  "editor.fontSize": 14,
  // Indent width
  "editor.tabSize": 4,
  // Format on save
  "editor.formatOnSave": true,
  // Word wrap
  "editor.wordWrap": "on",
  // Auto-save after delay
  "files.autoSave": "afterDelay",
  // Terminal font size
  "terminal.integrated.fontSize": 13
}

6.2 Settings Sync

After signing in with a GitHub or Microsoft account, you can enable Settings Sync as needed. The items that can be synced depend on the current version's UI, and usually include settings, keybindings, user snippets, and extension information, each of which can be enabled or disabled separately. It does not include project files and cannot replace Git or backups; remote extensions in WSL, SSH, and dev containers also need to be verified in the corresponding target environment.

7. Other Editors

This section uses VS Code; you can also use other editors and IDEs.

7.1 Editor vs IDE

The boundary between the two kinds of tools is not absolute: VS Code can provide debugging and refactoring after installing language extensions, and IDEs can also slim down their interface and plugins. The selection criteria should be project support, language toolchain, team conventions, and resource usage, not the tool category itself.

7.2 Recommendations

Specific features, system requirements, and licensing policies change over time; check the product's official website before installing. A student license does not mean the product is free forever.

8. TODO Checklist

• Know the difference between plain text, rich text, and typesetting documents
• Can tell encoding, decoding, and transcoding apart, and understand how UTF-8 / GBK mojibake arises
• Can download and install VS Code on your own, and switch it to the Chinese interface
• Can use "Reopen with Encoding" to check mojibake instead of directly overwriting and saving
• Can view and switch a file's encoding in the editor
• Try multi-cursor, project-wide search, and previewing replacement results
• Try downloading and installing a JetBrains IDE such as CLion, and do some simple exploration and use (for example, try something new, like a World, Hello!).

9. Questions Worth Thinking About