How can i determine error in matlab by using error loop without try catch or other loops?

My code only includes numbers. If someone donot gives a numbers in input, this code shows screen like ERROR but code should continue to work Thanks,

Answer 1

[Azzi Abdelmalek]

a=input('enter a number N','s')
b=str2num(a)
if isempty(b) 
  'Error'
  'presse any key to cotinue'
  pause
end

[Walter Roberson]

str2double would be better for restricting to numbers. you would check for nan rather than isempty

Answer 2

[ahmet ozdemir]

Thanks for comment. Actually, it is not empty. For example Enter the number:4+5 9 Enter the number:4-9 -5 Enter the number:4+ (((()))) ERROR Enter the number:h+4 ERROR

If input includes h and empty parenthesis, this code will gives error. I finished all steps but i didnot do error part