How to write a program that selectively picks hexadecimal values from a text file based on bit size?

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Akana Juliet 2021-6-15

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评论： Akana Juliet 2021-6-15

Hello all! I have a text file that is full of 16bit, 32bit, 64bit, and 128bit hexadecimal values, and I was trying to write a program that asks user the bit-size, then once the size is selected, a random hexadecimal value from the text file is spit out. I was thinking about if statements, but nothing I try is working. Any help or guidance would be greatly appreciated!

Edit Sorry! I have added the text file, but it is 4 hex values per a line, then enter. There are a lot more values than this in the real one but it follows same format

Edit#2

I am mostly confused with syntax for the bit selector, but I was thinking something like:

read file,

user selects bit mode (4 options)

if 16bit --> rand

if 32bit --> rand

if 64bit -->rand

if 128bit -->rand

if anything else, error

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Akana Juliet 2021-6-15

@Scott MacKenzie Actually, it's more like

lines 1-20 are all 16bit

lines 21-40 are all 32bit

lines 41-60 are all 64bit

lines 61-80 are all 128bit

Sorry for the lack of context in my question! I hope this helps convey. Thanks so much for helping me

Scott MacKenzie 2021-6-15

OK thanks. I see that @David Hill has just posted an succinct answer. Good luck.

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采纳的回答

David Hill 2021-6-15

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在 MATLAB Online 中打开

r=randi(4);
a=readcell('hextest.txt');
x=input('hex length: ');
hexValue=a{log2(x/16)+1,r};

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David Hill 2021-6-15

在 MATLAB Online 中打开

Yes. If you don't want any repetitions, use randperm.

r=randperm(4,3);%selects 3 in random order from 1:4
a=readcell('hextest.txt');
x=input('hex length: ');
hexValue=a(log2(x/16)+1,r);%output is a cell array

Akana Juliet 2021-6-15

Thank you so much for your help @David Hill ! I just have one final question, what am I doing wrong with my print statement? I'm only seeing 1 random value posted?

r=randi(4,3);

a=readcell('anothertest.txt');

x=input('Enter bit length: ');

hexValue=a{log2(x/16)+1,r};

fprintf('%s %s %s\n', hexValue);

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