switch statements and trig function
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val = str2double(input('enter number','s'));
chr = input('enter letter','s');
switch chr
case 's'
disp(sin(val))
case 'c'
disp(cos(val));
case 't'
disp(tan(val));
otherwise
disp('Oh no! Try a different character.');
end
I wrote this code to find the sin,cos,or tan of an entered individual number. I now need to modify it so that instead of reading a single character/number, the program continually reads character/number pairs and displays the trigonometry result. If a number outside the range [-100, 100] is entered, the program should not display the trigonometry result and should ask for another character/number pair to be entered. I can't figure out how to make the initial modifications of reading in pairs - any shortcuts I can use?
2 Comments
Answers (2)
Kevin Chng
on 24 Jan 2019
I think the most simple approach is to add another loop which is
val = str2double(input('enter number','s'));
chr = input('enter letter','s');
if val>=-100 && val<=100
switch chr
case 's'
disp(sin(val))
case 'c'
disp(cos(val));
case 't'
disp(tan(val));
otherwise
disp('Oh no! Try a different character.');
end
else
warning('enter new input, your input is out of range')
end
2 Comments
Kevin Chng
on 24 Jan 2019
I might miss understanding your question.
you may consider to use inputdlg, https://www.mathworks.com/help/matlab/ref/inputdlg.html
However, it is still input them in separate line, if wants to input in the same line, later, you might need to separate them since one is string/char and the other one is numeric
clc;clear all;
chr = input('enter letter & number :','s');
% Need some logic to separate them and ensure the user key in the right thing
C = {'1','2','3','4','5','6','7','8','9','0'};
for i = 1:10
Index = strfind(chr, C{i});
if isempty(Index)~=1
if exist('thefirstdigit')==0
thefirstdigit=Index;
else
if thefirstdigit>Index
thefirstdigit=Index;
end
end
end
end
%indexing to chr, then separate them into val and chr2
val = str2double(chr(thefirstdigit:end));
chr2 = (chr(1:thefirstdigit-1));
if val>=-100 && val<=100
switch chr2
case 's'
disp(sin(val))
case 'c'
disp(cos(val));
case 't'
disp(tan(val));
otherwise
disp('Oh no! Try a different character.');
end
else
Run the program and enter :s100
Kevin Phung
on 24 Jan 2019
Edited: Kevin Phung
on 24 Jan 2019
you can just run the input once, and evaluate the input as a whole.
word = input('enter letter followed by number','s');
if numel(word)>1
chr = word(1);
val =str2num(word(2:end))
if isempty(val) || val >100 || val < -100 %occurs when 2nd character is a letter and not a number
disp('Try again')
return
end
switch chr
case 's'
disp(sin(val))
case 'c'
disp(cos(val));
case 't'
disp(tan(val));
otherwise
disp('Oh no! Try a different character.');
end
else
disp('Try again')
end
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