shrsv:

I'm in a rambling mood right now, so this'll be a bit long.

First, I'd suggest that you pay a little more attention to the formatting of your code. I've reformatted it in two ways. First I put a blank line between the input section, the processing section and the output section to make the boundaries between them a bit more obvious. I also indented the nested code blocks:

#!/usr/bin/perl   
print "Enter a number\n";
chomp($a=<stdin>);
print "Enter second number\n";
chomp($b=<stdin>);
print "Enter third number\n";
chomp($c=<stdin>);
       
$big=0;
$equal=0;
if($a eq $b){
    $big = $a;
    $equal = $a;
}      
elsif($a > $b){
    $big=$a;
}      
else{  
    $big = $b;
}
 
if($equal eq $c){                                                     
+                    
    print "All numbers are same";
}      
elsif($big < $c){ 
    $big = $c;
}      
else{  
    print "The biggest number is $big \n";
}
[download]

Having done so, it's easier to see at least one of the errors: In your reporting section, one of your if branches doesn't print anything, so if you entered 1, 2, 3 as your numbers, then $big would be less than $c, and nothing would be printed:

$ perl 878546.pl
Enter a number
1
Enter second number
2
Enter third number
3

$
[download]

The way I'd suggest repairing it would be to move the middle case into the processing section, so you complete all your processing before reporting anything:

#!/usr/bin/perl   
print "Enter a number\n";
chomp($a=<stdin>);
print "Enter second number\n";
chomp($b=<stdin>);
print "Enter third number\n";
chomp($c=<stdin>);
        
$big=0; 
$equal=0;         
if($a eq $b){     
        $big = $a;
        $equal = $a;
}       
elsif($a > $b){   
        $big=$a;  
}       
else{   
        $big = $b;
}       
if ($big < $c) {  
        $big = $c;
}       
        
if($equal eq $c){
        print "All numbers are same";
}       
else{                                                                 
+                    
        print "The biggest number is $big \n";
}
[download]

The next immediately apparent error is that you're trying to use $equal for two purposes, which is often a bit tricky. For example, check out this test case:

$ perl 878546.pl
Enter a number
1
Enter second number
2
Enter third number
0
All numbers are same
[download]

The problem is that you're trying to use $equal to be a flag to tell when the numbers are equal and to hold the value. But since you can enter any value for $c, you can get stuck. So I'd suggest using $equal as a simple yes/no flag. You can use $big to hold the value when they're equal, since if the values are equal, then $big will hold the correct value anyway. So to fix this bug, I'd change the code to something like:

#!/usr/bin/perl    
print "Enter a number\n";  
chomp($a=<stdin>); 
print "Enter second number\n";
chomp($b=<stdin>); 
print "Enter third number\n";
chomp($c=<stdin>); 
        
$big=0; 
$equal=0;                                                             
+                    
if($a eq $b){
        $big = $a;
        $equal = 1;
}       
elsif($a > $b){
        $big=$a;
}       
else{   
        $big = $b;
}       
if ($big < $c) {
        $big = $c;
}       
if ($big != $c) {
        $equal = 0;
}       

if($equal == 1){
        print "All numbers are same";
}       
else{   
        print "The biggest number is $big \n";
}
[download]

Here's a test case that'll show you another error, but I'll leave the solution to you, as I don't want to spoil the fun. Enter " 1", "1" and "1 " (without the quotes--they're just there to show you which blanks you'll want to enter), and you'll see that the program won't tell you that the numbers are all the same.

Finally, I'll make a suggestion: Make your program take an arbitrary number of input values.

Have fun!

...roboticus

When your only tool is a hammer, all problems look like your thumb.