what is the different...

[broloc]

could someone please tell me the different of these variable.
1. '=='
2. 'eq'
3. 'defined( a = b)'

i would be very appreciate if someone could help me.

 

[PerlIsGood]

Hi broloc,

1. '==' is Perl's NUMERIC comparison operator

  $num1 = 9;
  $num2 = 9;
  if ( $num1 == $num2 ) { ...do stuff; }

2. 'eq' Same as '==', but comparing STRINGS

  $string1 = "NAME";
  $string2 = "NAME";
  if ( $string1 eq $string2 ) { ...do stuff; }

If you use 'eq' on numeric values, or vice-versa, the return value will most likely not be what you expected.

3. ... ..confused by question... But 'defined' is generally used in an expression to check whether or not a variable has been 'defined', (i.e., is not a NUL value). So I guess

  if ( defined($a = $b)) { ..do stuff; }

would be checking to make sure the results of that expression evaluate to 'something' before it enters the if block... Not sure though. I've never tried it Notorious P.I.G.

 

[broloc]

i have one problem...my script cannot compare the local time with the time that user give.here is my coding:

#!/usr/local/bin/perl

$time = 0;
open(FILE,'readme.txt')||die$!;
$realtime = <FILE>;

while (defined($realtime != $time) ) {
open(FILE,'readme.txt')||die$!;
$realtime = <FILE>;
($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime(time + (3600*$timeoffset));

@days = qw(Sunday Monday Tuesday Wednesday Thursday Friday Saturday);
@months = qw(1 2 3 4 5 6 7 8 9 10 11 12) ;
$year = $year + 1900;

$time= &quot;$mday/$months[$mon]/$year&quot;;
print &quot;$time\n&quot;;
if ($realtime eq $time) {
print &quot; this is the time....running schedule\n&quot;;
open(HANDLE,'config.dat')||die$!;
$data = <HANDLE>;
$mday = $mday + $data;
if ( $mday > 365) {
$year = ($data / 365) + $year;
$mday = $mday - $data;
}
elsif ($mday > 31) {
while ( $mday > 31) {
$mday = $mday - 31;
$months[$mon] = $months[$mon] + 1;
if ($months[$mon] > 12 ) {
$months[$mon] = $months[$mon] - 12;
$year = $year + 1;
}
}
}
$realtime = &quot;$mday/$months[$mon]/$year&quot;;
open(FILE,'>readme.txt')||die$!;
print &quot;$realtime\n&quot;;
print FILE &quot;$mday/$months[$mon]/$year&quot;;
close FILE;
exit;
}
else {
print &quot;this is not the time to run any program\n&quot;;
open(FILE,'readme.txt')||die$!;
$data = <FILE>;
print &quot;the next program will be run on &quot;;
print &quot;$data\n&quot;;
sleep(10);
}
}

could someone tell me what is wrong with this coding....