How to count and display the number of input?

Question

Roxanne Esguerra 2020-7-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560813-how-to-count-and-display-the-number-of-input

评论： Roxanne Esguerra 2020-7-12

采纳的回答： Monisha Nalluru

在 MATLAB Online 中打开

Hi, I need help with displaying the count of the input given in the error message.

Here is my code,

function num = posnum;
num = input('Enter a positive number: ');
n = nargin;
while num<0
    fprintf('Error # %.0f : Follow Instructions!\n',n)
    fprintf('Does %.2f look like a positive number to you?\n',num)
    num = input('Enter a positive number: ');
    if num>0
    squarerootvalue = sqrt(num);
    end
end
end

My code displays:

>> squarerootvalue = posnum

Enter a positive number: -8

Error # 0 : Follow Instructions!

Does -8.00 look like a positive number to you?

Enter a positive number: -7

Error # 0 : Follow Instructions!

Does -7.00 look like a positive number to you?

Enter a positive number: 4

squarerootvalue =

4

However, it should display Error #1, then Error#2, Error#3, and so on...

Also, the final answer must be the square root of the input number...

What changes must be done to code?

Thanks in advance!

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

dpb 2020-7-7

在 MATLAB Online 中打开

function num = posnum;
num = input('Enter a positive number: ');
n = nargin;
while num<0
  fprintf('Error # %.0f : Follow Instructions!\n',n)
  ...

Reread the documentation for nargin -- it provides only the number of arguments with which a function is called -- and your function has no arguments so it rightfully returns 0--and if you tried to pass an argument, the call to the function would fail for that reason.

You're not interested in how many arguments are being passed to the function at all.

You'll need to keep an internal counter and increment it in the error section of the code.

Also, the above code could never output the last line shown -- the trailing semicolon suppresses output and there's nothing else to output anything -- and it surely appears the answer this case should be 2.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Monisha Nalluru 2020-7-10

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560813-how-to-count-and-display-the-number-of-input#answer_463946

在 MATLAB Online 中打开

nargin returns the number of input arguments given to a function while executing.

So, in the above problem you have passed zero input arguments. This is the reason why it is displayed as Error # 0 : Follow Instructions! Every time.

And the output of the function is just the number you passed as input. You found the square root value but not assigned as output.

You can make use of following example

function squarerootvalue = posnum
num = input('Enter a positive number: ');
i=0;
while num<0
    i=i+1;
    fprintf('Error # %.0f : Follow Instructions!\n',i);
    fprintf('Does %.2f look like a positive number to you?\n',num);
    num = input('Enter a positive number: ');
end
squarerootvalue=sqrt(num); % Output of function which is squarerrotvalue
end