MATLAB: How to convert decimal into binary

Question

Hello,

I need to convert n-bit decimal into 2^n bit binary number. I do not have much idea. Can anybody help me please?

Answer 1

This code shows '11111111' only, because you overwrite the output in each iteration:

n= 8;
for i = 0:2^n-1
   x = dec2bin(i,8);
end

Therefore x contains the last value only: dec2bin(2^n-1, 8).

Better:

x = dec2bin(0:2^n-1, 8);

Or if you really want a loop:

n = 8;
x = repmat(' ', 2^n-1, 8);  % Pre-allocate
for i = 0:2^n-1
   x(i+1, :) = dec2bin(i,8);
end
x

[EDITED] If you want the numbers 0 and 1 instead of a char matrix with '0' and '1', either subtract '0':

x = dec2bin(0:2^n-1, 8) - '0';

But to avoid the conversion to a char and back again, you can write an easy function also:

function B = Dec2BinNumeric(D, N)
  B = rem(floor(D(:) ./ pow2(N-1:-1:0)), 2);
end

PS. You see, the underlying maths is not complicated.