while loop with OR statement

2015 12 5
1 个回答
回答已采纳
更新时间：2015 12 9
4 次查看（30 天）

0 个投票

I am trying to ask a user input a real, positive number by using input function and checking the condition with a while loop. I am successful to check is the number is real and positive but I could not figure out how to correct if the user inputs a character.
K=input('Enter the K value = ', 's');
% I ask as string because if the user enters a character I want to give warning
%rather than code is not working.
K=str2num(K); % convert string to a number
sK=size(K); % if K is a character its size will be 0 0
sK=sK(1);
while (isnan(K)) || (any(imag(K)))|| ((K<=0))
disp('Number of domains input needs to be real and positive')
K=input('Enter the K value = ', 's');
K=str2num(K);
sK=size(K);
sK=sK(1);
end
% This while loop works but I can not check for if the input was a character
while (isnan(K)) || (any(imag(K)))|| ((K<=0)) || (sK==0) % get an error Operands to the || and && operators must be
%convertible to logical scalar values.
Any thoughts where I make a mistake?
(in the second while I can't write in the question , I dont know why. But I know there should be between statements) Thank you

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Kamuran
Kamuran 2015-12-5
编辑：Kamuran 2015-12-5
Or simpler problem I am having. I decided to separate the while loop into two while loops. In the first one I am checking if the user enter a alphabetic character first.
% Asking user to input the variable Out1=input(['Enter the beginning point of the domain = '],'s'); Out2=input(['Enter the ending point of the domain = '],'s');
Out1=str2num(Out1); sK1=size(Out1); % if OUT1 is not a number, sK1 will be 0 by 0 sK1=sK1(1); Out2=str2num(Out2); sK2=size(Out2); % if OUT2 is not a number, sK2 will be 0 by 0 sK2=sK2(1); while (sK1==0) (sK2==0)
Out1=input(['Enter the starting point of the domain = '],'s');
Out2=input(['Enter the ending point of the domain = '],'s');
Out1=str2num(Out1);
sK1=size(Out1);
sK1=sK1(1);
Out2=str2num(Out2);
sK2=size(Out2);
sK2=sK2(1);
end
This does not work ..but if I check 1 by 1 it does work ..I dont understand why.
Any suggestion?

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Image Analyst
Image Analyst 2015-12-5

0 个投票

Here is the snippet I use:
% Ask user for two floating point numbers.
defaultValue = {'45.67', '78.91'};
titleBar = 'Enter a value';
userPrompt = {'Enter floating point number 1 : ', 'Enter floating point number 2: '};
caUserInput = inputdlg(userPrompt, titleBar, 1, defaultValue);
if isempty(caUserInput),return,end; % Bail out if they clicked Cancel.
% Convert to floating point from string.
usersValue1 = str2double(caUserInput{1})
usersValue2 = str2double(caUserInput{2})
% Check for a valid number.
if isnan(usersValue1)
% They didn't enter a number.
% They clicked Cancel, or entered a character, symbols, or something else not allowed.
% Convert the default from a string and stick that into usersValue1.
usersValue1 = str2double(defaultValue{1});
message = sprintf('I said it had to be a number.\nI will use %.2f and continue.', usersValue1);
uiwait(warndlg(message));
end
It should be easy to modify to handle just one input instead of 2.

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Characters and Strings 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by