Convert a String of 0-F into a Byte Array in Ruby

Converting a binary value to hexadecimal in Ruby

How about:

>> "0x%02x" % "0000111".to_i(2) #=> "0x07"
>> "0x%02x" % "010001111".to_i(2) #=> "0x8f"

Edit: if you don't want the output to be 0x.. but just 0.. leave out the first x in the format string.

How do I convert a 32-bit binary string to float in ruby

Does this work?

t = <binary-string-returned-here>
result = (t[2..3] + t[0..1]).unpack('F')[0]

ruby - How can I generate an array of every combination of letters and numbers of a given length?

alphanum = [*?a..?z, *?0..?9]
length.times.flat_map { |l|
  alphanum.repeated_permutation(l + 1).map(&:join)
}

Note that length > 3 will give you a lot of results.

EDIT: As meagar says, this is very memory-intensive. An Enumerator-based answer (not as pretty, but won't kill your memory):

e = Enumerator.new do |y|
  length.times do |l|
    alphanum.repeated_permutation(l + 1).each do |p|
      y << p.join
    end
  end
end

Convert Hex Chars into a String of Bits (Python or Ruby)

In Ruby:

yourbits = "026219AAF80F440206025019AAF816A944274480"[-2,2].to_i(16).to_s(2)
=> "10000000"
puts yourbits
10000000
=> nil

Explaining each step -- first, slice the string to get the last 2 characters:

"026219AAF80F440206025019AAF816A944274480"[-2,2]
=> '80'

Convert it to Integer:

"80".to_i(16)
=> 128

Back to string againg, in a binary representation:

128.to_s(2)
=> '10000000'

There's probably a better (or less confusing) way of doing it, but I can't imagine it right now.

Code golf - hex to (raw) binary conversion

edit Checkers has reduced my C solution to 46 bytes, which was then reduced to 44 bytes thanks to a tip from BillyONeal plus a bugfix on my part (no more infinite loop on bad input, now it just terminates the loop). Please give credit to Checkers for reducing this from 77 to 46 bytes:

main(i){while(scanf("%2x",&i)>0)putchar(i);}

And I have a much better Ruby solution than my last, in 42 38 bytes (thanks to Joshua Swank for the regexp suggestion):

STDIN.read.scan(/\S\S/){|x|putc x.hex}

original solutions

C, in 77 bytes, or two lines of code (would be 1 if you could put the #include on the same line). Note that this has an infinite loop on bad input; the 44 byte solution with the help of Checkers and BillyONeal fixes the bug, and simply stops on bad input.

#include <stdio.h>
int main(){char c;while(scanf("%2x",&c)!=EOF)putchar(c);}

It's even just 6 lines if you format it normally:

#include <stdio.h>
int main() {
  char c;
  while (scanf("%2x",&c) != EOF)
    putchar(c);
}

Ruby, 79 bytes (I'm sure this can be improved):

STDOUT.write STDIN.read.scan(/[^\s]\s*[^\s]\s*/).map{|x|x.to_i(16)}.pack("c*")

These both take input from STDIN and write to STDOUT

How can I reliably transpose an array of chars to an array of uint64_t and back again

In this answer I will address the actual question:

having problems obtaining 64 bits blocks from the input file

...rather than the one addressed so far:

after reading my file into a buffer, my CharArrayToInt64() function replaces large portions of the input buffer with F.

I recommend (IMHO) that you read the file directly into a uint64_t array / buffer, rather than copy the data from a byte array.

While an unsigned char array you might encounter memory alignment concerns, a uint64_t array is guaranteed to be correctly memory aligned and you only need to worry about padding...

...Oh, and please use the unsigned versions, as indicated by others on this thread, this is what's causing the shifting issues.

Once both arrays (encryption and decryption) use the same unsigned type, your code will look much cleaner.

Good luck.

How to add up all objects (sum) of an array (with decimal) and display result in UILabel?

Your sum variable is an int type, so the decimal portion will be truncated (not rounded- simply dropped off). Instead, sum should be a double or float type.

float sum=0;
for(int x=0; x < [priceArray count]; x++)
{
    sum += [[priceArray objectAtIndex:x] floatValue];
}

budgetLabel.text = [NSString stringWithFormat:@"$%.2f", sum];

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