concatenation problem

[archulu]

hai this is archulu. i have a problem in my program as for cancatintion the values.

use strict;
use warnings;
 
my $string = 'N/W_Administrator/Trinee';
 
my $str = 'Level1';
my $len1 = 1;
#my $len1 = 1;    
 
my $a=length($string);
 
if ($a < 15) {
    my $length = 4;
    my $frag = substr $string, 0, $length;
    print "fragment: $frag\n";
 
} else {
    my $lengt = 7;
    my $frag = substr $string, 0, $lengt;
    print "fragment: $frag\n";
}
 
my $frag1 = substr $str, 0, $len1;
my $frag2 = substr $str, 5;
my$sub=$frag."".$frag1."".$frag2;
 
print "frag1: $frag1\n";
print "frag2:$frag2\n";
print "values are:$sub\n";
 

this my program . in ths my progra i want to cancatinate frag(which come from loop as o/p) and frag1 and frag2
but i have a error like this

Global symbol "$frag" requires explicit package name at proj.pl line 28.
Execution of proj.pl aborted due to compilation errors.

i am saved my program as a proj.pl name
plz help to me solve this error

[prn]

Hi archulu,

Your problem is that $frag is declared within a block delimited by the {} following the "if". Therefore that declaration "my $frag" is local to that block, so when you reference $frag later outside its scope, the Perl interpreter (correctly) complains. You need to declare $frag globally if you need to use it globally. (And don't redeclare it within the block or you will be assigning to a different variable with the same name and local scope!):

my $frag;
if ($a < 15)
{
  $frag = substr $string, 0, 4;
}
...
my $sub=$frag.$frag1.$frag2;  
#There's no need to concatenate null strings here.

HTH,
Paul

[KevinADC]

Paul has explained the error message. But there is also no need for your if/else block at all. Use the ternary operator to define the value of $a (changed to $length below). You really should not use $a or $b except with the sort() function.

use strict;
use warnings;
 
my $string = 'N/W_Administrator/Trainee';
 
my $str = 'Level1';
my $len1 = 1;
 
my $length = length($string) < 15 ? 4 : 7; 
my $frag = substr $string, 0, $length;
print "fragment: $frag\n";
 
 
my $frag1 = substr $str, 0, $len1;
my $frag2 = substr $str, 5;
my $sub   = "$frag$frag1$frag2";
 
print "frag1: $frag1\n";
print "frag2: $frag2\n";
print "values are: $sub\n"; 

[archulu]

thank u so much sir it very help to me