OK this one sounds like it should be a natural...
it must be possible to send a number say 200 to a text file and later use it as a variable?
yada yada > file.txt
how would I retrieve that number to use as a variable? Is this possible? (5 Replies)
Logic of code
if ( $var is a number ) {
Do something
}
else {
Do something else
}
My question is: How do I check if a variable is a number. All the reg ex that I came up with to match this is failing. Please help. (3 Replies)
I'm working on formatting some attendance data to meet a vendors requirements to upload to their system. With some help on the forums here, I have the data close. But they've since changed what they want.
The vendor wants me to submit three fields to them. Field 1 is the studentid field,... (4 Replies)
Hello All,
A part of my very basic perl code requires me to read a single value from a text file.
The file output is the following:
Reading image ... done
IMAGEREGION=0x0x0-256x162x256
VOXELDIMENSION=0.9375000000x1.2000000477x0.9375000000
VOXELNUMBER=10527001... (7 Replies)
I have a file which is delimetered by ',' i need to filter out a file with respect to the number of fileds in each line.
a,s,d,f,g,h,j,k,l
1,2,3,3,4,5,6,7,6
a,2,3
4,5,6,7
in this
i neeed to filter out the lines with 8 column to another file and rest to another file.
so
... (3 Replies)
Hi,
I am new to unix. I need to insert a variable which contains some lines of text into a text file after fixed number of lines..
Please help me on this..
Thanks in Advance,
Amrutha (3 Replies)
In the hello.htm have the sentenses:
Hello $name
How are you?
The perl script:
$name = "David";
open(HEADER,"hello.htm");
while(<HEADER>) { $html .= $_; }
close(HEADER);
print "$html";I making something about template. But it can't process the $name variable. (4 Replies)
Hy!
I need to post-process some data files which have variable (and periodic) number of fields. For example, I need to square (data -> data*data) the folowing data file: -5.34281E-28 -3.69822E-29 8.19128E-29 9.55444E-29 8.16494E-29 6.23125E-29
4.42106E-29 2.94592E-29 1.84841E-29 ... (5 Replies)
So, I have three problems that cover this subject.
First one asks me to find the number of fields in the file that contain the substring "he". I found the number of fields, but the problem I have is that they are displaying by each record. I want to add all of the records' fields together.
With... (2 Replies)
Discussion started by: mc10
2 Replies
LEARN ABOUT OSX
fields
fields(3pm) Perl Programmers Reference Guide fields(3pm)NAME
fields - compile-time class fields
SYNOPSIS
{
package Foo;
use fields qw(foo bar _Foo_private);
sub new {
my Foo $self = shift;
unless (ref $self) {
$self = fields::new($self);
$self->{_Foo_private} = "this is Foo's secret";
}
$self->{foo} = 10;
$self->{bar} = 20;
return $self;
}
}
my $var = Foo->new;
$var->{foo} = 42;
# this will generate an error
$var->{zap} = 42;
# subclassing
{
package Bar;
use base 'Foo';
use fields qw(baz _Bar_private); # not shared with Foo
sub new {
my $class = shift;
my $self = fields::new($class);
$self->SUPER::new(); # init base fields
$self->{baz} = 10; # init own fields
$self->{_Bar_private} = "this is Bar's secret";
return $self;
}
}
DESCRIPTION
The "fields" pragma enables compile-time verified class fields.
NOTE: The current implementation keeps the declared fields in the %FIELDS hash of the calling package, but this may change in future
versions. Do not update the %FIELDS hash directly, because it must be created at compile-time for it to be fully useful, as is done by
this pragma.
Only valid for perl before 5.9.0:
If a typed lexical variable holding a reference is used to access a hash element and a package with the same name as the type has declared
class fields using this pragma, then the operation is turned into an array access at compile time.
The related "base" pragma will combine fields from base classes and any fields declared using the "fields" pragma. This enables field
inheritance to work properly.
Field names that start with an underscore character are made private to the class and are not visible to subclasses. Inherited fields can
be overridden but will generate a warning if used together with the "-w" switch.
Only valid for perls before 5.9.0:
The effect of all this is that you can have objects with named fields which are as compact and as fast arrays to access. This only works as
long as the objects are accessed through properly typed variables. If the objects are not typed, access is only checked at run time.
The following functions are supported:
new perl before 5.9.0: fields::new() creates and blesses a pseudo-hash comprised of the fields declared using the "fields" pragma into
the specified class.
perl 5.9.0 and higher: fields::new() creates and blesses a restricted-hash comprised of the fields declared using the "fields" pragma
into the specified class.
This function is usable with or without pseudo-hashes. It is the recommended way to construct a fields-based object.
This makes it possible to write a constructor like this:
package Critter::Sounds;
use fields qw(cat dog bird);
sub new {
my $self = shift;
$self = fields::new($self) unless ref $self;
$self->{cat} = 'meow'; # scalar element
@$self{'dog','bird'} = ('bark','tweet'); # slice
return $self;
}
phash
before perl 5.9.0:
fields::phash() can be used to create and initialize a plain (unblessed) pseudo-hash. This function should always be used instead of
creating pseudo-hashes directly.
If the first argument is a reference to an array, the pseudo-hash will be created with keys from that array. If a second argument is
supplied, it must also be a reference to an array whose elements will be used as the values. If the second array contains less
elements than the first, the trailing elements of the pseudo-hash will not be initialized. This makes it particularly useful for
creating a pseudo-hash from subroutine arguments:
sub dogtag {
my $tag = fields::phash([qw(name rank ser_num)], [@_]);
}
fields::phash() also accepts a list of key-value pairs that will be used to construct the pseudo hash. Examples:
my $tag = fields::phash(name => "Joe",
rank => "captain",
ser_num => 42);
my $pseudohash = fields::phash(%args);
perl 5.9.0 and higher:
Pseudo-hashes have been removed from Perl as of 5.10. Consider using restricted hashes or fields::new() instead. Using
fields::phash() will cause an error.
SEE ALSO
base
perl v5.16.2 2012-10-11 fields(3pm)