Mastering Indentation in Vim: A Comprehensive Guide

Indentation is a fundamental aspect of writing clean and readable code. In Vim, a powerful text editor favored by many developers for its efficiency and flexibility, mastering indentation can significantly enhance your coding workflow. This tutorial will guide you through various methods to indent multiple lines quickly in Vim, leveraging both normal and visual modes, as well as command-line instructions.

Introduction to Indentation in Vim

Indentation in Vim is controlled primarily through the shiftwidth setting, which defines the number of spaces used for each indentation level. You can set this in your .vimrc file with:

set shiftwidth=4

This command sets the indentation width to 4 spaces. Other related settings include expandtab, which converts tabs into spaces, and autoindent, which maintains the indentation of the previous line.

Basic Indentation Commands

1. Indenting a Single Line:

   • Use >> to indent the current line by one shiftwidth.
   • Use << to de-indent it.

2. Indenting Multiple Lines:

   • To indent multiple lines, prefix the command with a number: 5>> indents five lines.
   • Similarly, use 5<< to de-indent them.

3. Re-indenting Blocks:

   • Place your cursor on a brace { or bracket [, then use > followed by % to increase indentation of the entire block.
   • Use = followed by % to re-indent the block according to Vim’s settings.

Visual Mode Indentation

Visual mode is particularly useful for selecting and indenting multiple lines at once:

1. Select Lines:

   • Enter visual line mode with V.
   • Move up or down using j or k to select additional lines.

2. Indent the Selection:

   • Press > to indent the selected block.

Indenting Using Markers

Markers in Vim allow you to mark positions and perform actions between them:

1. Set a Marker:

   • Use ma to set a marker ‘a’ at your starting point.

2. Move to End Position:

   • Navigate to the end of the block you want to indent.

3. Indent Between Markers:

   • Execute >'a to indent from marker ‘a’ to the current position.

Indenting Entire Files or Multiple Buffers

For larger projects, you might need to re-indent entire files:

1. Re-indent Current Buffer:

   • Use gg=G to re-indent the entire file based on your indentation settings.

2. Batch Process Multiple Files:

   • List all relevant files with :args *.c.
   • Run :argdo normal gg=G followed by :wall to save changes.

3. Re-indent All Open Buffers:

   • Execute :bufdo normal gg=G | wall.

Indenting in Insert Mode

While in insert mode, you can adjust indentation:

• Use <C-t> to increase and <C-d> to decrease the indentation at the start of a line.
• To remove all indentation from a line, press 0<C-d>.

Ex Commands for Specific Ranges

Vim’s Ex command interface allows precise control over indentation ranges:

• Apply indentation with :4,8>> to indent lines 4 through 8.

Intelligent Indentation Based on Filetype

Vim can automatically adjust its behavior based on the file type. Enable filetype detection and plugins in your .vimrc:

if has("autocmd")
    filetype plugin indent on
endif

This ensures that Vim uses appropriate indentation rules for different programming languages.

Conclusion

Mastering these techniques will make you more efficient at managing code structure in Vim, allowing you to focus more on writing quality code. Experiment with these commands and settings to find the workflow that best suits your development style.