Character to Binary function?

Question

Andrew Ardolino 2014-11-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/163995-character-to-binary-function

编辑： Thorsten 2014-11-26

I need to create a function that will: accept a character and returns a vector of 8 logical values (bits) that are the binary equivalent of the ASCII value of the character, while using functions dec2bin, sprintf, and logical. While converting the 0's and 1's to ASCII codes, we aren't supposed to use a if statement, we're supposed to follow these rules:

If you have the character '0' (which in Matlab is the same as the number 48), how would you convert that 48 into a 0? In other words, how do you get from 48 to 0? How do you get from 49 to 1? Or for that matter, how would you get from 50 to 2? The relationship is the same in each case.

I'm not sure where to get started on this function, any help would be great, thanks in advance!!

From what I understand, we need to accept a character, then convert it to ASCII (not sure how to do this), then output a vector of 8 bits (0s and 1s). So far, I know a 0 is 48 in ASCII, but when I use dec2bin, i get:

110100

111000

So i'm not really sure where to go from there.

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Answer 1

Image Analyst 2014-11-24

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编辑：Image Analyst 2014-11-24

在 MATLAB Online 中打开

Subtraction seem like the obvious operation that they were hinting strongly at. Did you try subtraction:

ch = '0' % or anything from '0' - '9'
decimalValue = ch - '0'
dec2bin(ch) % Binary of the ascii value.
dec2bin(decimalValue)  % Binary of the decimal value

I trust you can take it from there.

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Image Analyst 2014-11-24

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I'm going to assume what I said is true - that you want a logical array. So the function below handles both cases of ASCII and decimal, since I'm not clear which one you want. Please adapt if necessary.

function [decimalLogicalArray, asciiLogicalArray] = char2bin()
  clc;
  userInput = input('Enter a numerical digit : ', 's')
  % userInput is the ASCII value of the digit.  So for 2, the value is 50.
  decimalValue = userInput - '0'
  % Get the binary value of the ascii value of the digit in a string (a character array).
  % For example, for 2, strAscii will be 110010 (which = 50 in decimal).
  strAscii = dec2bin(userInput) % Binary of the ascii value.
  % Get the binary value of the decimal value of the digit in a string (a character array).
  % For example, for 2, strDecimal will be 10 (which = 2 in decimal).
  strDecimal = dec2bin(decimalValue)  % Binary of the decimal value
  % Convert the binary string into a logical array.
  % So for example, 2 = 50 = 110110 will be a logical array [1,1,0,1,1,0]
  asciiLogicalArray = logical(strAscii-'0')
  % So for example, 2 = 10 will be a logical array [1,0]
  decimalLogicalArray = logical(strDecimal-'0')

Andrew Ardolino 2014-11-24

but I need to be able to use characters as well as digits, and i need to force the vector to be 8 digits long

Image Analyst 2014-11-25

在 MATLAB Online 中打开

This works bot both numbers and characters in a string. For example '123abc'.

function asciiLogicalArray = char2bin()
clc;
userInput = input('Enter a numerical digit : ', 's')
% userInput is the ASCII value of the digit.  So for 2, the value is 50.
decimalValue = userInput
% Get the binary value of the ascii value of the 
% characters in a string (a character array).
% For example, for 2, strAscii will be 110010 (which = 50 in decimal).
strAscii = dec2bin(userInput) % Binary of the ascii value.
% Convert row-wise to a row vector
strAscii = reshape(strAscii', [1, numel(strAscii)])
% Convert the binary string into a logical array.
% So for example, 2 = 50 = 110110 will be a logical array [1,1,0,1,1,0]
asciiLogicalArray = logical(strAscii - 48)

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Answer 2

Thorsten 2014-11-24

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c = input('Enter a character > ', 's');
binvecc = logical(dec2bin(c, 8) - '0');
sprintf('%x', binvecc)

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Andrew Ardolino 2014-11-24

nevermind, I think this works. is ascii involved with this? can you explain the -'0' to me?

Thorsten 2014-11-26

编辑：Thorsten 2014-11-26

c is represented as an ASCII value.

dec2bin returns a array of characters, e.g. '0110001'. To convert this into numbers you have to subtract '0', which works on every character in the array. Just as [ 1 2 3] - 4 works in Matlab.

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