tcl regexp根据字符串的索引匹配数字字符串

Question

I am in need of a little help. I am trying to come up with a regexp to match a string of digits. I want the string to match starting at a position value of the string I have.

here is the string I have

01102000000000001A40000000200000000000100012064000100000000000000

I want the regexp to match starting from the 20th value of the string or directly after the A4. Also I want to match the first say 10 digits after the 20th value of the string. I have tried a few things they are not really working. Wanted to see if I could get some idea's here.

Answer 1

In case the link in TessellatingHeckler's answer goes stale, I'll add another answer with the actual code. There are at least three solutions to this problem (assume the string to search in is in the variable s ):

TessellatingHeckler's solution:

lindex [regexp -inline {.{19}(\d{10})} $s] 1

Another regexp solution:

regexp -inline -start 19 {\d{10}} $s

A string range solution:

string range $s 19 19+9

Documentation: lindex , regexp , string

Answer 2

A regex to match the first 19 characters up to A4 and throw them away, then capture 10 digits after that into a group:

.{19}(\d{10})

http://regex101.com/r/cO9bE7/1

(I don't know if it's TCL compatible, though).