On 9/12/11 Mon Sep 12, 2011 12:47 PM, "Ryan Munson" <ryan.barrac...@elboardo.com> scribbled:
> The full exercise states: > > Write a program that asks for a decimal number less than 256 and converts > it to binary. (Hint: You may want to use the bitwise and operator 8 times.) > > Since 256 is 2^8, I am assuming using a computation of 2**8 is involved. I don't see where 2**8 is involved anywhere. Decimal and binary are two different ways of representing integer numbers. The number represented by decimal '17' is also represented by binary '010001' ( and octal '21'). The 'bitwise-and' operator allows you to query the status of individual bits in the binary representation of a number. If your decimal number has been assigned to the Perl variable $dec, then the expression ($dec & 1) will be true if the lowest bit of the binary form of $dec is 1. Likewise, ($dec & 2) will be true if the second-lowest bit of $dec is 1, and so on up to ($dec & 128). Since your number is supposed to be "less than 256", i.e. 255 or less, you will only need 8 bits to represent all possible binary numbers (from 0 to 255). Normally, rather than doing 8 separate similar things, a programmer will write a loop that is iterated 8 times. However, if your book says or implies that you do this exercise without if statements or loops, you may have to have 8 different explicit expressions using the bitwise-and, each statement testing a different bit of $dec. With this information and what Brandon has given you, can you attempt to rewrite your program? Cheat1: Perl printf has the %b descriptor that will print any integer in binary form. Cheat2: You are not the first person to have trouble with this exercise: <http://www.perlmonks.org/?node_id=780435> Good luck! -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
