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Why this simple script showing wired output

expertalert
New User

Mar 31, 2010, 2:08 AM

Post #1 of 3 (243 views)

Why this simple script showing wired output	Can't Post

Hi bellow is a simple script.

after putting usernanme:fosiul, password: pass
the out put is coming like this :
pass1fosiul11

Or

demopass1demon11

can any one please tel me what causing this problem??
thanks for your time and help

Code

 
#!/usr/bin/perl -T 
use strict; 
 
use CGI qw/:standard/; 
 
my $data =  new CGI; 
 
my $user = $data->param('name'); 
my $pwd  = $data->param('pass'); 
 
if($user ne '') 
{ 
 
print header, 
print $user, 
print $pwd, 
print end_html; 
exit; 
} 
 
else 
{ 
print header, 
start_html('Hello'), 
start_form(-method=>'POST',-action=>"/cgi-perl/mylogin.pl"), 
"Enter your name: ",textfield('name'), 
"Enter your Password: ",textfield('pass'), 
submit, 
end_form, 
hr, 
 
 
}

Nila
User

Mar 31, 2010, 4:06 AM

Post #2 of 3 (234 views)

Re: [expertalert] Why this simple script showing wired output [In reply to]	Can't Post

Try this,

Code

if($user ne '')  
{  
  
print header,  
$user,  
$pwd; 
print end_html;  
exit;  
}

If you want format output you can use header tag like,

Code

h1($user,$pwd);

7stud
Enthusiast

Mar 31, 2010, 7:00 AM

Post #3 of 3 (225 views)

Re: [Nila] Why this simple script showing wired output [In reply to]	Can't Post

This:

Code

print header,  
print $user,  
print $pwd,  
print end_html;

is equivalent to:

Code

print(header, print $user, print $pwd, print end_html);

In any programming language, when a function call is encountered in the code, the function is executed, and then the function call is replaced by the function's return value. print() is a function. print() returns 1 if the content was successfully printed.

As a result, the last code example is executed like this:

1) perl sees the print() on the left, and perl starts stepping through the list of the things that are supposed to be printed.

2) perl prints the header.

3) print ($user) is a function call, so perl stops doing whatever it was doing and executes the function. Then perl replaces the function call with its return value, which is 1, giving you this:

print (header, 1, .....);

So perl prints the 1.

4) print($pwd) is a function call, so perl stops doing whatever it was doing and executes the function. Then perl replaces the function call with its return value, which is 1, giving you this:

print (header, 1, 1, ...);

etc.

To correct your problem, you can do either this:

Code

print  header,  start_html,  $user,  $pwd,  end_html;

which is easier to read if you format it like this:

Code

print   
    header,   
    start_html("A page title"), 
    $user, 
    $pwd,   
    end_html, 
;

And because you should put an html tag around everything you send to a browser, it would be better like this:

Code

print   
    header,   
    start_html("A page title"), 
    div($user), 
    div($pwd),   
    end_html, 
;

Or you can do this:

Code

print header; 
print start_html("A page title"); 
print div($user); 
print div($pwd); 
print end_html;

You are going to want to use this too:

Code

use CGI::Carp qw{fatalsToBrowser};

(This post was edited by 7stud on Mar 31, 2010, 7:19 AM)

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