whats wrong with this if block?

% WHATS WRONG WITH THIS IF BLOCK, AM NOT GETTING UNKNOWN AS A RESULT WHERE
%  IT HAS TO GIVE  ME THIS RESULT. WHEN i JUST RUN THIS CODE, IT GIVE ME THIS ERROR MESAGE:
%  Index exceeds matrix dimensions.

different_salts_available=input(['Enter the number associated with the chloride that is available with ZnBr2 and HCOONa, enter 0 if another chloride salt than the ones listed are available,'...
            '\n1: NH4Cl,'...
            '\n2: MgCl2,'...
            '\n3: CaCl2,'...
            '\n4: NaCl,'...
            '\n5: KCl.  ']);
        
if (different_salts_available==1||2||3||4||5)
  det_beste_saltet='ZnBr2';
  disp('Choose to add zinc bromide,')
  disp(det_beste_saltet)
else
  det_beste_saltet='unknown';
  disp('Invalid number entered. The programme cannot decide the best salt based on the input entered. The best salt is:')
  disp( det_beste_saltet)
end 
            

Answer 1

[dpb]

(different_salts_available==1||2||3||4||5)

is bad syntax for if in MATLAB. It results in testing the result of the logical expression

(different_salts_available==1) || 2 || 3 || 4 || 5

which is always TRUE so nothing matters about what the variable value actually is.

MATLB requires the form as

if different_salts_available==1 || different_salts_available==2 || different_salts_available==3 ...

which is very verbose; you could write

if ismember(different_salts_available,1:5)

as one possible way or

if different_salts_available>=1 & different_salts_available<=5

or several other alternatives.

The latter is common enough expression I have a utility routine iswithin I use quite a bit to hide some higher level complexity

function flg=iswithin(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = iswithin(x,lo,hi)
%      returns T for x between lo and hi values, inclusive

  flg= (x>=lo) & (x<=hi);
end

With it, the latter above becomes

if iswithin(different_salts_available,1,5)
  ...