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Posted on 2004-04-09
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Hello experts,

I just start with perl language few days ago.  I need to know what does the & symbol means in the folowing script:

#!/usr/bin/perl
                                                                                                                             

push @array, (1,2,3)[6 & 10];
                                                                                                                             
                                                                                                                             
print @array;

------------------
result: 3

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what I know that the push function pushes the values of list onto the end of array.  ANd number in square bracets point to list index .   Can somebody give me a hint.

thanks

luxana
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Question by:Luxana
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davorg earned 120 total points
ID: 10789957
& is the "bitwise and" operator. It compares the binary representation of two numbers and returns the number that has bits set only where the same bit is set in _both_ of the input numbers.

So, in your example:

6 is 0110 in binary.
10 is 1010 in binary.

They only have one bit in common, so a bitwise and opertion returns 0010. Converting that to decimal gives 2.

So 6 & 10 is 2.

Your code therefore becomes:

push @array, (1,2,3)[2];
                                                                             
print @array;

Which has the same effect as:

push @array, 3;

There is also a "bitwise or" operator which returns a set bit where either of the inputs have a set bit. 6 | 2 is 1110 (which is 14) and a "bitwise exclusive or" which returns a set bit where only on of the inputs have a set bit. 6 ^ 2 is 1100 (which is 12).

See "perldoc perlop" for more details.

Dave...
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by:Luxana
ID: 10790190
Dave ,

I got it:))) You have no idea how many things I tried. Perfect so now I can move on:)))

Thanks for your help Dave

LUXANA

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