Is there a command or package to search for all instances of asubstring in a string?

[Peng Yu]

Hi,

Can somebody let me know if there is a command or function to find all
the occurance of a substring in a string? I can write a program to do
this. I just want to know what is the best way to do this.

Thanks,
Peng

 

[John W. Krahn]

Can somebody let me know if there is a command or function to find all
the occurance of a substring in a string? I can write a program to do
this. I just want to know what is the best way to do this.

perldoc -f m
perldoc -f index
perldoc -f rindex


John

 

[Tad J McClellan]

Can somebody let me know if there is a command or function to find all
the occurance of a substring in a string?

What does "find" mean when you say it?

If string="aaa" and substring="aa", should it "find" the substring 1 or 2 times?

I just want to know what is the best way to do this.

That depends entirely on what "this" is...

If "this" is:

find all of the starting indexes of a substring in a larger string

then to find non-overlapping substrings:

push @indexes, pos($string) - length $substr, while $string =~ /$substr/g;

or to find overlapping substrings:

for (my $pos = -1; {
$pos = index $string, $substr, $pos+1;
last if $pos == -1;
push @indexes, $pos;
}

 

[Jürgen Exner]

Can somebody let me know if there is a command or function to find all
the occurance of a substring in a string? I can write a program to do
this. I just want to know what is the best way to do this.

perldoc -f index

and keep looking ( aka looping)

jue

 

[Ilya Zakharevich]

[A complimentary Cc of this posting was sent to
Tad J McClellan

find all of the starting indexes of a substring in a larger string

then to find non-overlapping substrings:

push @indexes, pos($string) - length $substr, while $string =~ /$substr/g;

One should keep in mind that overlapping substrings can be done in the
same way:

push @indexes, pos($string) - length $substr, while $string =~ /(?=$substr)/g;

# As above, $substr should not contain metachars; otherwise \Q\E may
be needed...

Hope this helps,
Ilya