Fastest way to remove the first x characters from a very long string

[Rustom Mody]

On Saturday, May 16, 2015 at 8:30:02 PM UTC+5:30, Grant Edwards wrote:
> On 2015-05-16, bruceg113355 wrote:
> 
> > I have a string that contains 10 million characters.
> >
> > The string is formatted as:
> >
> > "0000001 : some hexadecimal text ... \n
> > 0000002 : some hexadecimal text ... \n
> > 0000003 : some hexadecimal text ... \n
> > ...
> > 0100000 : some hexadecimal text ... \n
> > 0100001 : some hexadecimal text ... \n"
> >
> > and I need the string to look like:
> >
> > "some hexadecimal text ... \n
> > some hexadecimal text ... \n
> > some hexadecimal text ... \n
> > ...
> > some hexadecimal text ... \n
> > some hexadecimal text ... \n"
> >
> > I can split the string at the ":" then iterate through the list
> > removing the first 8 characters then convert back to a string. This
> > method works, but it takes too long to execute.
> >
> > Any tricks to remove the first n characters of each line in a string faster?
> 
> Well, if the strings are all in a file, I'd probably just use sed:
> 
> $ sed 's/^........//g' file1.txt >file2.txt
> 
> or
> 
> $ sed 's/^.*://g' file1.txt >file2.txt


And if they are not in a file you could start by putting them (it) there :-)

Seriously... How does your 'string' come into existence?
How/when do you get hold of it?