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Programming Perl

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3.2.109 pos

pos SCALAR

Returns the location in SCALAR where the last m//g search over SCALAR left off. It returns the offset of the character after the last one matched. (That is, it's equivalent to length($`) + length($&).) This is the offset where the next m//g search on that string will start. Remember that the offset of the beginning of the string is 0. For example:

$grafitto = "fee fie foe foo";
while ($grafitto =~ m/e/g) {
    print pos $grafitto, "\n";
}

prints 2, 3, 7, and 11, the offsets of each of the characters following an "e". The pos function may be assigned a value to tell the next m//g where to start:

$grafitto = "fee fie foe foo";
pos $grafitto = 4;  # Skip the fee, start at fie
while ($grafitto =~ m/e/g) {
        print pos $grafitto, "\n";
}

This prints only 7 and 11. (Thank heaven.) The regular expression assertion, \G, matches only at the location currently specified by pos for the string being searched.


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