switch case syntax need

[EDIT: Wed May 25 04:59:27 UTC 2011 - Reformat - MKF]

I want a switch build a switch case statement as follows:

switch value
   case {10-100}
      disp('Method is within 100')
   case {101-500}
      disp('Method is within 500')   
   otherwise
      disp('Unknown method.')
end

my problem is how to set case statement to check within the range 10 to 100 or 101 to 500. Thanks in advance.

Answer 1

[Matt Fig]

Why would you want to do this with a SWITCH instead of an IF-ELSEIF structure?

N = 131;

switch ((N>=10 && N<=100) + 2*(N>=101 && N<=500))
    case 1
        disp('Method is within 100')
    case 2
        disp('Method is within 500')         
    otherwise
        disp('Unknown method.')
end

The following approach seems more natural to me, and is more efficient if used many times with an even distribution of cases. This is because the first conditional will be the only one evaluated when it is true, but in the SWITCH statement both conditionals are evaluated every time.

if (N>=10 && N<=100)
    disp('Method is within 100')
elseif (N>=101 && N<=500)
    disp('Method is within 500')
else
    disp('Unknown method.')
end

[Walter Roberson]

I'm not sure that it is true that each case is evaluated every time, but I cannot check at the moment.

I know that if you have multiple matching case labels, only the first will performed.

[Mohammad Golam Kibria]

Thanks

Answer 2

[Walter Roberson]

switch value
   case num2cell(10:100)
      disp('Method is within 100')
   case num2cell(101:500)
      disp('Method is within 500')   
   otherwise
      disp('Unknown method.')
end

[Mohammad Golam Kibria]

your code works if my value is a natural number not for real number.Thanks

[Walter Roberson]

If you want to handle real numbers, then why do you use the "otherwise" behavior for (value>100 & value<101) ? When we see obvious natural numbers in use, we are justified in providing a solution that only works for natural numbers.

Anyhow, here's the alternative:

switch true

case value >=10 && value <=100

disp('Method is within 100')

case value >=101 && value<=500

disp('Method is within 500');

otherwise

disp('Unknown method.')

end

[david feilacher]

genius !!

[Walter Roberson]

Note that for (value > 100 & value < 101) that you would hit the Otherwise. I would suggest that the problem was not created properly for real values:

switch true
case value >=10 && value <=100
disp('Method is within 100')
case value >100 && value<=500
disp('Method is within 500');
otherwise
disp('Unknown method.')
end