How can I use vim regex to replace text when math division is involved in expression
I am using vim to process text like this
0x8000 INDEX1 ....
0x8080 INDEX2 ....
....
0x8800 INDEXn ....
I want to use a regex to get the index number of each line. i.e
0x8000 ~ 0
0x8080 ~ 1
....
0x8800 ~ n
The mathematical score should be (hex - 0x8000) / 0x80. I am trying to use vim regex replacement to get the result in a string
%s/^\(\x\+\)/\=printf("%d", submatch(1) - 0x8000)
This will give
0 INDEX0
128 INDEX1
....
2048 INDEXn
What I want to do is change it to
0 INDEX0
1 INDEX1
...
20 INDEXn
That is, I want to still split the first column 0x80. This is when I get the problem.
The original argument is "send (1) - 0x8000". Now I add "/ 0x80" to it, which forms
%s/^\(\x\+\)/\=printf("%d", (submatch(1) - 0x8000)\/0x80)
Now the Vim error message
Invalid expression: printf("%d", (submatch(1) - 0x8000)\/0x80))
It looks like vim is having a problem handling the "/". I also tried with one "/" (no exit) but still doesn't work.
Can anyone help me with this?
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You cannot use a separator character in sub-replace-expression
.
From :h sub-replace-expression
:
Be careful: The separation character must not appear in the expression! Consider using a character like "@" or ":". There is no problem if the result of the expression contains the separation character.
Instead, change the delimiter so that it no longer matches the division operator. For example use #
.
:%s#^\(0x\x\+\)#\=printf("%d", (submatch(1) - 0x8000)/0x80)
Please note that I had to change your regex (specifically ^\(\x\+\)
to ^\(0x\x\+\)
). I don't know why yours works for you, but from :h character-classes
, \x
shouldn't include the final 0x
:
/\x \x \x hex digit: [0-9A-Fa-f]
Also, your regex is a little easier to read (at least for me) using very magic mode (see :h magic
):
:%s#\v^(0x\x+)#\=printf("%d", (submatch(1) - 0x8000)/0x80)
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