MATLAB Answers

Mark Grano

re entering a user inputted variable

Asked by Mark Grano
on 27 Oct 2012

hello, i just have one very very minor issue with another area in which i need to make sure the number is ten digits long after everything is taken out, and if it is not ten digits long, it needs to ask to enter stra again and re run the program.

i have clear;clc;

stra =input('Enter a 10 digit phone number: ','s');
nbrs = regexpi(stra, '\d');
nbrx = stra(nbrs);
if length(nbrx)<10
      clear;clc;    disp('Invalid input'); strb=input('Please enter a TEN digit phone number: ','s');     stra=strb;end

although when i run this fragment i get an error. any thoughts on how to fix this? i imagine its simple. its just when i re enter stra it does not put it through the first part of the program that converts stra into what nbrx is. i get an error that nbrx is undefined.


In the case where you re-input, you do not recalculate nbrs or nbrx, but the "clear" has removed their original values.

why won't it re-calculate it? shouldn't it re input stra back into all the previous functions with the new value?

No. When you have an expression such as

nbrx = stra(nbrs);

then nbrx would be calculated with the values of stra and nbrs that were active right at the time the statement executed, and no "history" of having been calculated from stra and nbrs would be recorded and "replayed" to recalculate nbrx when new values were assigned to any of the variables. If you want to recalculate nbrx then you need to have another executable statement that calculates it.

And besides, remember that you "clear" in the meantime: if history of how nbrx had been kept somehow, you would have asked to have erased it by executing the "clear".


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1 Answer

Answer by Image Analyst
on 27 Oct 2012
 Accepted answer

Here's one way to do it:

defaultValue = '(123)456 - 7890';
titleBar = 'Enter the number';
userPrompt = 'Enter the 10 digit phone number';
numberCount = 0;
while numberCount < 10
	% Ask user for a number.
	caUserInput = inputdlg(userPrompt, titleBar, 1, {num2str(defaultValue)});
	if isempty(caUserInput),return,end; % Bail out if they clicked Cancel.
	strInput = char(caUserInput)
	numberCount = 0;
	theNumber = [];
	[a1 a2 a3 a4 a5 a6 indexes] = regexpi(strInput, '\d')
	numberCount = length(a4)
	onlyTheNumbers = char(a4)
	fprintf('The numbers = %s\n', onlyTheNumbers);


i like your style with the menu. i want to learn how to use those in my projects. but this works great except for i don't want it to calculate anything when the user enters less than ten digits. it needs to say that it was invalid and ask the user to re enter the number. the rest of the program actually produces the keytones that sound when you actually dial them on a phone. just so you don't think thats the whole program haha. thanks again

nevermind, i just realized that it works perfect! haha, i thought it was still running the numbers through the program even if there wasn't enough, but it wasn't.

Thank you!

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