Add / Replace New values, Hash structure

Tutorials

Perl

Topic

How to Adding Elements to a Hash structure?
How to replace the same key with different values using Hash?

Explanation

Accessing an element in a hash structure is similar to that from an array, except we replace square brackets with curly ones and instead of an index, the key is used.

     print $name{Tom};

In the above example Tom is equivalent to 'Tom'.To add a new scalar value use the following code.

     $name{Tom} = value;

Example:

    #! C:\programfiles\perl\bin\perl
    print "content-type: text/html\n\n";
    %name = ('Tom' => 26, 'Peter' => 51, 'Jones' => 23);
    print "Before Adding:<br>";  
    # In a loop print the hash                      
    while (($key, $value) = each(%name))
    {
      print $key.", ".$value."<br/>";
    }
    # Add a key "Sam" with value "31" is added
    $name{Sam} = 31;    
    # Add a key "Peter" with value "90" is added
    $name{Peter} = 90;  
    print "After Adding:<br>";
    #In a loop print the new hash
    while (($key, $value) = each(%name)) 
    {
      print $key.", ".$value."<br/>";
    }

Result:

    Before Adding values:
    Jones, 23
    Peter, 51
    Tom, 26
    After Adding values:
    Jones, 23
    Peter, 90
    Sam, 31
    Tom, 26

In the above example we are adding the same key ie., "Peter" with a different value ie., "90", so the key is replaced with the new value using a hash structure.

Add /Replace New values to Hash in Perl