# How to convert decimals to Ascii characters?

6 views (last 30 days)
Jefe on 30 Sep 2022
Edited: James Tursa on 30 Sep 2022
So I have a char with a bunch of decimals in each line, these decimals go from 0 to 63. I'm trying to convert these decimals to the one that represents it in the image below. So 0 should be changed to A, 1 should be changed to B and so on. Anyone know if there are some functions to make this easier?

John D'Errico on 30 Sep 2022
Edited: John D'Errico on 30 Sep 2022
The ascii encoding is not what you are asking to find, since this produces a different result.
D = 0:63;
char(D + 'A')
ans = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'
However, nothing stops you from using a simple lookup table.
CharLut = ['A':'Z','a':'z','0':'9','+/']
CharLut = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
Now you can evaluate any set of integers through that lut.
N = randi(63,[1,50])
N = 1×50
32 15 58 4 11 56 51 28 37 14 47 14 20 47 54 24 16 21 7 48 43 55 52 8 15 25 39 28 6 34
CharLut(N+1)
ans = 'gP6EL4zclOvOUv2YQVHwr30IPZncGie5P0GaMCDsVlCxb/v63p'
Dont forget that MATLAB uses a 1 index origin, so you need to add 1.

James Tursa on 30 Sep 2022
Edited: James Tursa on 30 Sep 2022
Your table isn't ASCII encoding of characters, so you can't use simple functions such as double( ) etc. You are probably going to have to write your own conversion function. I would suggest looking at the ismember( ) function using the 2nd Locb output. E.g. start with this char string:
S = ['A':'Z','a':'z','0':'9','+','/']
S = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
Then you can use this for mapping back & forth between the numbers and the characters, offsetting the index by 1. E.g.,
c = 'THEstring'
c = 'THEstring'
[~,N] = ismember(c,S); % From char string to numbers
x = N-1 % Offset by 1
x = 1×9
19 7 4 44 45 43 34 39 32
C = S(x+1) % From numbers back to char string, offset by 1
C = 'THEstring'
It would also help if you provided example inputs and desired outputs in your question so we know exactly what you want.