How to convert hex number '0' to binary when it is at first place in a bit stream

hex_str='0123';

actual answer is 0000000100100011 but matlab is not showing the starting zeros as it giving the answer 10010011

[Walter Roberson]

How are you doing the conversion?

[kamila]

by using the command hex2dec then dec2bin

Answer 1

[Azzi Abdelmalek]

s='0123'
b=strjoin(cellfun(@(x) dec2bin(hex2dec(x),4),regexp(s,'.','match'),'un',0),'')

Answer 2

[Joseph Cheng]

reading the documentation on dec2bin you can specify the number of bits

>> hexstr= '0123';
>> n=length(hexstr);
>> d = hex2dec(hexstr);
>> dec2bin(d,2^n)

[kamila]

Thank you MR. Joseph CHENG it really help us

[Joseph Cheng]

You're welcome, however i don't understand the statement "it really us"

[Joseph Cheng]

Again you're welcome, i wasn't sure if there were more to the statement Q('-')9

[kamila]

how can I apply this to hex_str='0123456789ABCDEF'