How to recognize it is uppercase ,lowercase , or other sign ?

what's wrong here ? why it does'nt work properly ???

prompt = "Pls Enter a character"
ease enter an latter: ";
a = input(prompt,"s");

if (a>="65" || a<="90")
    fprintf("this is UPPERCASE \n ");
    
elseif (a>="97" || a<="122")
    fprintf("leading character \n");
    
else 
        fprintf("It is  %s\n",a);
end 

Answer 1

[Stephen23]

Your logic is incorrect, you should be using &&, not ||

Also you are comparing against strings of the character values, whereas you should either compare against the characters themselves or against the character numeric values. It makes no sense to compare against strings of the character values.

So you should be doing either one of these:

a>=65  && a<=90
a>='A' && a<='Z'

By the way, here is a much simpler vectorized method to detect upper/lower case letters:

>> v = 'aBCde$';
>> isup = lower(v)~=v
isup =
  0  1  1  0  0  0
>> islo = upper(v)~=v
islo =
  1  0  0  1  1  0

Another simple option is to call isstrprop:

>> isstrprop(v,'upper')
ans =
  0  1  1  0  0  0
>> isstrprop(v,'lower')
ans =
  1  0  0  1  1  0

[Mahmoud Elbeltagy]

nice way of thinking, i really liked the second way :)