ITNW 2310 - PERL
Allan Kochis,Adjunct Professor - CIT

Strings

  1. length
    PerlOutput 
    #!/usr/bin/perl -w
#
#
while(<>) {
   chomp;
   $a=$_;
   $long=length($a);
   print $long." bytes = ".$a."\n";
}


    $ ./pl9a1.pl
hello
5 bytes = hello
hello there
11 bytes = hello there
hello
10 bytes = hello
the rain in Spain
17 bytes = the rain in Spain

  2. index
    PerlOutput 
    #!/usr/bin/perl -w

$string="To be or not to be that is the question.";

$at=index($string,"the");

print qq/"the" Found at byte $at \n/;

$start=0;
do {
    $at=index($string,"be",$start);
    if($at ne -1 ) {
        print qq/"be" Found at byte $at \n/;
        $start=$at+1;
    }
} while($at != -1);


    "the" Found at byte 27
"be" Found at byte 3
"be" Found at byte 16

  3. rindex
    PerlOutput 
    #!/usr/bin/perl -w

$string="To be or not to be that is the question.";

$at=rindex($string,"the");

print qq/"the" Found at byte $at \n/;

$start=length($string)-1;
do {
    $at=rindex($string,"be",$start);
    if($at ne -1 ) {
        print qq/"be" Found at byte $at \n/;
        $start=$at-1;
    }
} while($at != -1);


    "the" Found at byte 27
"be" Found at byte 16
"be" Found at byte 3

  4. substr
    PerlOutput 
    #!/usr/bin/perl -w
#
#
#
$string="ACC UNIX Class";
#       +01234567890123  left to right
#        32109876543210  right to left

print "String\t".$string."\n";

print "String 0,1\t".substr($string,0,1)."\n";
print "String 4,10\t".substr($string,4,10)."\n";
print "String 4\t".substr($string,4)."\n";

print "String -5\t".substr($string,-5)."\n";
print "String -5,2\t".substr($string,-5,2)."\n";

#
# now use substr as lvalue
#
substr($string,4,4)="Perl";
print "String replace\t".$string."\n";

#
# use substr as lvalue and limit changes
#
substr($string,0,3) =~ tr/A-Z/a-z/;
print "String with tr\t".$string."\n";


    String	ACC UNIX Class
String 0,1	A
String 4,10	UNIX Class
String 4	UNIX Class
String -5	Class
String -5,2	Cl
String replace	ACC Perl Class
String with tr	acc Perl Class

  5. tr
    PerlOutput 
    #!/usr/bin/perl -w

$string="To be or not to be that is the question.";

$string=~ tr/ /:/;

print $string."\n";

$string=~ y/:/ /;

print $string."\n";


    To:be:or:not:to:be:that:is:the:question.
To be or not to be that is the question.
© Allan Kochis Last revision 10/19/2005