Pattern Matching: Integer Validation
MATCHING SCRIPT:
<![CDATA[
#!/usr/bin/perl
$line = "tenacious often tendency attention forgotten attend";
print "LIST: $line\n";
print "---------------------------------\n";
print "BEGINNING OF WORD:\n";
@hold = ($line =~ /\bten[^ ]*/g);
foreach $item ( @hold ){
print "$item\n";
}
print "---------------------------------\n";
print "END OF WORD:\n";
@hold = ($line =~ /[^ ]*ten\b/g);
foreach $item ( @hold ){
print "$item\n";
}
print "---------------------------------\n";
print "INSIDE WORD:\n";
@hold = ($line =~ /[^ ]*\Bten\B[^ ]*/g);
foreach $item ( @hold ){
print "$item\n";
}
exit;
]]>
EXCLUSION GROUPS:
<![CDATA[
[^eE]
CHARACTER-RANGE ESCAPE SEQUENCES:
\d Any digit [0-9]
\D Anything other than a digit [^0-9]
\w Any word character [_0-9a-zA-Z]
\W Anything not a word character [^_0-9a-zA-Z]
\s Whitespace [ \r\t\n\f]
\S Anything other than whitespace [^ \r\t\n\f]
MATCHING ANY CHARACTER:
.*
MATCHING SPECIFIED OCCURRENCES:
/de{1,3}f/ def, deef, deeef
/de{3}f/ deeef
/de{3,}f/ deeef, deeeef, deeeeef, etc.
/de{0,2}f/ df, def, deef
.{3} three of any letter
SPECIFYING CHOICES:
/def|ghi/ def OR ghi
[a-z]+|[0-9]+ matches one or more lowercase letters or one or more digits
SIMPLE INTEGER VALIDATION PROGRAM:
#!/usr/bin/perl
print "ENTER NUMBER: ";
$n = <STDIN>;
chomp($n);
while($n ne "q"){
if($n =~ /^\d+$/ ){
print "LEGAL\n\n";
}
else{
print "NOT A NUMBER\n\n";
}
print "ENTER NUMBER: ";
$n = <STDIN>;
chomp($n);
}
exit;
]]>