Simple operations using the default register
#51
Vim’s default register makes it easy to perform some of the most basic types of cut, copy, and paste operations. That’s partly thanks to the p command, which behaves differently depending on whether the default register contains a characterwise or linewise region of text.
Toggling characters
When I’m typing, I frequently make this sort of error: I hit all the right keys, but in the wrong order.
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It’s easily fixed. I’ll place my cursor on the first of the two characters that I want to exchange, then press xp.
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2uagain, but slowly.xcuts a single character, copying it into Vim’s default register.pgets the contents of the default register and puts that text into the document after the cursor position.
Even though x and p are two discrete commands, you can think of xp as meaning toggle characters, as though it were a single command.
Toggling lines
We can just as easily toggle the order of lines. Here’s a list of upcoming Vimcast episodes:
Default register operations Using named registers Meet the yank register
I’d like to swap the order of the 2nd and 3rd items. I’ll put my cursor on the first of the lines I want to exchange, then press ddp:
Simple operations using the default register Meet the yank register Using named registers
dd cuts the current line, copying it into Vim’s default register. As before, p gets the contents of the default register and puts that text into the document after the cursor.
Just as xp can be thought of as toggle characters command, ddp can be thought of as toggle lines.
Charwise vs linewise
Between these two examples, there’s a subtle difference in the behavior of the p command. In the first instance, the default register contained a characterwise region of text, so the p command put the text after the current character. In the second instance, the default register contained a linewise region, so the p command put the text after the current line. It doesn’t matter if the cursor is on the first or last character of the line, and that’s really convenient!
Watch what happens when I do a linewise cut-n-paste in a basic text editor. I’ll select the entire line and cut it. Now the paste command works fine so long as my cursor is at the start of the line, but if my cursor is anywhere else then the result is messy!
Duplicating lines
We can also use Vim’s default register to quickly duplicate a line, by pressing yyp:
Pasting text from Visual mode Pasting text from Visual mode
yy copies the line into the default register. p does the same as before, putting the text from the default register after the current line.
Just as ddp can be thought of as a toggle lines command, yyp can be thought of as a duplicate line command.
Outro
Common operations such as these are made easy by Vim’s default register, which is paradoxically called the ‘unnamed register’ in the documentation:
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Vim has many more registers besides the default register. We’ll learn more about them in the next episodes.