Backtracking in Regular Expression
What is Backtracking in Regular Expression?
Explanation
Storing the matching patterns for future use is known as Backtracking.
#! C:programfilesperlbinperl
print "content-type: text/htmlnn";
$string = '17-12-76 12:30:15';
if ($string =~m/([0-9]+-[0-9]+-[0-9]+) ([[0-9]+:[0-9]+:[0-9]+)/)
{
print "The Date of Birth is '$1'.n";
print "<br>";
print "The Date is '$2'.n";
} Result :
The Date of Birth is '17-12-76'.
The Date is '12:30:15'.
In the above example, we have two matching patterns one for the date, then for a time, and the values returned when there is a match can be referred anywhere using "$1" for the first pattern, "$2" for the second pattern.
Example :
#! C:programfilesperlbinperl
print "content-type: text/htmlnn";
$string = '17-12-76 12:30:15';
if ($string =~m/([0-9]+-[0-9]+-[0-9]+) ([[0-9]+:[0-9]+:[0-9]+)/)
{
print "The Date of Birth is '$1'.n";
print "<br>";
print "The Date is '$2'.n";
}
The Date of Birth is '17-12-76'.
The Date is '12:30:15'.
In the above example, we have two matching patterns one for the date, then for a time, and the values returned when there is a match can be referred anywhere using "$1" for the first pattern, "$2" for the second pattern.
