问题
I am using vim to process text like the following
0x8000 INDEX1 ....
0x8080 INDEX2 ....
....
0x8800 INDEXn ....
I want to use regular expression to get the index number of each line. that is
0x8000 ~ 0
0x8080 ~ 1
....
0x8800 ~ n
The math evaluation should be (hex - 0x8000) / 0x80. I am trying to using vim regular expression substitution to get the result in line
%s/^\(\x\+\)/\=printf("%d", submatch(1) - 0x8000)
This will yield
0 INDEX0
128 INDEX1
....
2048 INDEXn
What I want to do is to further change it to
0 INDEX0
1 INDEX1
...
20 INDEXn
That is, I want to further divide the first column with an 0x80. Here is when I get the problem.
The original argument is "submatch(1) - 0x8000". I now add an "/ 0x80" to it, which forms
%s/^\(\x\+\)/\=printf("%d", (submatch(1) - 0x8000)\/0x80)
Now Vim report error
Invalid expression: printf("%d", (submatch(1) - 0x8000)\/0x80))
It looks like vim meet problem when processing "/". I also tried with a single "/" (without escape), but still fails.
Can anyone help me on this?
回答1:
You can't use the separation character in a 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 separator to no longer match the division operator. E.g., use #.
:%s#^\(0x\x\+\)#\=printf("%d", (submatch(1) - 0x8000)/0x80)
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 trailing 0x :
/\x \x \x hex digit: [0-9A-Fa-f]
Also, your regex is a bit easier to read (to me at least) using very-magic mode (see :h magic):
:%s#\v^(0x\x+)#\=printf("%d", (submatch(1) - 0x8000)/0x80)
来源：https://stackoverflow.com/questions/30072389/how-can-i-use-vim-regex-to-replace-text-when-math-divide-is-involved-in-the-expr