MATLAB Answers

nested if else statements

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Cyrus
Cyrus on 25 Jul 2013
Commented: Jan on 21 Aug 2017
Can someone write an example of a nested if else statement? matlab keeps underlining the 'else' when I try to write a nested 'if else' statement telling me the syntax is wrong.
Also, where do I put the 'end' for each of the 'if else' statements?

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Walter Roberson
Walter Roberson on 1 Mar 2017
Rohit, it is difficult for us to give an informed opinion without seeing the file in question.
BISHMITA SHARMA
BISHMITA SHARMA on 21 Aug 2017
May be u are writing the expression in the next line after 'ifelse' try writing it in the same line... because there will be only one 'end', for the first 'if'
Jan
Jan on 21 Aug 2017
@BISHMITA SHARMA: I assume the problem is solved already, because this thread was written 4 years ago.

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Accepted Answer

Evan
Evan on 25 Jul 2013
Edited: Evan on 25 Jul 2013
x = 5.5
if x > 6
disp('x is greater than 6')
elseif x >= 3 && x <= 6
if mod(x,1) ~= 0
disp('x is a non-integer value between 3 and 6')
else
disp('x is a integer value between 3 and 6')
end
elseif x < 3
disp('x is less than 6')
end
The above code checks to see what range x falls in, then enters an if/else statement that determines whether it is evenly divisible by one. If not, this means x is not an integer value and the corresponding text is displayed. Here, you could get rid of the nesting if you liked by using statements like elseif x >=3 && x <= 6 && mod(x,1) ~= 0, but eventually it would get messy and difficult to read.
%grade = [];
grade = 75;
if ~isempty(grade)
if grade > 70
disp('Assignment passed!')
else
disp('Assignment failed!')
end
else
disp('No grade found for this assignment!')
end
Here's another example in which we have to use the nesting in order to check for cases where a blank grade was given.

  3 Comments

Jan
Jan on 25 Jul 2013
No, if ~isempty(grade) && grade > 75 does not produce an error for empty grade. It is the purpose of the && operator to short-circuit, here not to evaluate the right part, if the left part is FALSE already.
Evan
Evan on 25 Jul 2013
Oops! I guess I'm remembering incorrectly. I'll remove the incorrect portion of my code. Hmm... I must've been thinking of a scenario where the class of the variable being compared led to an error in the second condition.
Jan
Jan on 26 Jul 2013
Thanks for the correction, Evan.

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More Answers (3)

Nathan Crosty
Nathan Crosty on 25 Jul 2013
Edited: Nathan Crosty on 25 Jul 2013
this = 222;
that = 111;
if this == 333
disp('this')
elseif that == 444
disp('that')
else
this = 555;
if this == 222
disp('this')
else
disp('that')
end
end

  1 Comment

Evan
Evan on 25 Jul 2013
Because the nested if statement contained within the else segment of the the outer statement has no option for "false" values, this would be more clear to display with an if/elseif statement rather than the nested version. Might be a bit misleading to use it as an example.

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Sohrab Abedini
Sohrab Abedini on 27 Dec 2015
Edited: Sohrab Abedini on 27 Dec 2015
The examples were great. However, I could not still find a solution to this problem of mine: I don't know how to write it in matlab code->
if n=4 then -> c=2, d=3 or c=3 , d=2.
I wondering if writing "or" is acceptable in result statement. it seems wrong but I have to do it somehow. --- The actual problem is changing a 2nd rank Tensor to a 4th rank tensor through Voigt mapping. which is quite easy vise versa and so difficult in this way. I might be able to solve it if I understand to write "or" or sth like that in if statement.

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Nava  Subedi
Nava Subedi on 26 Nov 2016
Edited: Stephen Cobeldick on 26 Nov 2016
Can someone help me to what is wrong with my code:
function [l, m, n] = sort3([a b c])
if a>=b && a>=c
if b>=c
l = c;
elseif b<=c
l = b;
else l = a;
end
elseif b>=a && b>=c
if a>=c
m = c;
elseif a<=c
m = a;
else m = b;
end
else c>=a && c>=b
if a>=b
n = b;
elseif a<=b
n = a;
else n = c;
end
end
I am trying to write nested if statement.

  1 Comment

Stephen Cobeldick
Stephen Cobeldick on 26 Nov 2016
This is not MATLAB syntax:
function [l, m, n] = sort3([a b c])
It looks like you are trying to write Python, or something similar. The correct MATLAB syntax is shown in the online beginners tutorials, the documentation, and lots of online forums:
function [l, m, n] = sort3(a, b, c)
Anyone can read the MATLAB documentation for free. It explains how MATLAB works:

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