CreateDialog[{TextCell["Enter number: "], 
              InputField[Dynamic[nm], Number], 
              DefaultButton[DialogReturn[ret = nm]]}];

ConstantArray[0, nm];

I get:

ConstantArray::ilsmn: Single or list of non-negative machine-sized integers expected at position 2 of ConstantArray[0,1].

and I do not know how to correct. Some idea? Thank you!

  • $\begingroup$ use ConstantArray[0, ToExpression@nm] or modify your InputField[...] to InputField[Dynamic[nm], Number]? $\endgroup$
    – kglr
    Commented Feb 3, 2018 at 18:04
  • $\begingroup$ Then you have some odd cached definition. As you have it it works for me. $\endgroup$
    – b3m2a1
    Commented Feb 3, 2018 at 19:52

1 Answer 1


In your example the ConstantArray[0, nm] is evaluated immediately after the creation of the dialog window, i.e. before you enter any input. What you need to do is have evaluations "pause" until you enter a number into the input window and the dialog closes. DialogInput is your friend.

  DialogNotebook[{TextCell["Enter number: "], 
    InputField[Dynamic[nm], Number], 

ConstantArray[0, nm]

While the above will "work" you need to add some checks of the input:

 ConstantArray[0, nm],
 Print["Hey you need to enter an integer"]

enter image description here


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