# help solving string question

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Joseph Pauwels on 7 May 2014
Answered: Joshua Amuga on 2 Nov 2016
Durring my last semester, we were given a bonus quiz to write a function the received and numberical input and produced the revise as an output.
example a=123
b=321
we were not allowed to use any string variable or function. Any ideas now that the semester is over Id like to know what you think.
My original thought was to divide the input but the got harder with larger number as the function should receive any number
##### 1 CommentShowHide None
Joseph Pauwels on 7 May 2014
boy it is a good thing this was not an English class. that spelling and miss used work are horrible. I am glad yall knew what I meant

Star Strider on 7 May 2014
This works, but obviously only for integers:
a = 123;
% a = fix(rand*1E6) % Test Integer
La = fix(log10(a));
x = a;
for k1 = La:-1:0
d(k1+1) = fix(x/(10^k1));
x = rem(x,10^k1);
end
v10 = 10.^(La:-1:0)';
Flipped_a = d*v10
The Flipped_a variable is the result. I tested it on other random integers as well.
Wesley Ooms on 8 May 2014
fix, log10, rand, and rem are functions. The way i read the question is that no function is allowed.

### More Answers (4)

Carlos on 7 May 2014
a=[1 2 3 4 5];
>> b=zeros(1,length(a));
count=1;
l=length(a);
while(count<=l)
b(count)=a(l+1-count);
count=count+1;
end
##### 1 CommentShowHide None
Joseph Pauwels on 7 May 2014
Thanks Carlos, that i could do. but not what i meant 12345 not 1 2 3 4 5.

Wesley Ooms on 7 May 2014
totally not optimized, but this will do the trick:
clear a b
a=32385
i=1
while floor(a/10)
b(i)=a-floor(a/10)*10
i=i+1
a =floor(a/10)
end
b(i)=a
d=1
e=0
for c=0:numel(b)-1
e=e+d*b(end-c)
d=d*10
end
Wesley Ooms on 8 May 2014
the following code also works but is faster for large numbers since it predetermines the size of the number
function b=swapnumber(a)
b=0;d=0;while a>1;a=.1*a;d=d+1;end
for i=0:d;c=0:a*10;c=c(end);b=b+c*10^i;a=a*10-c;end

Sagar Damle on 7 May 2014
Edited: Sagar Damle on 8 May 2014
I think the code which I am going to put here is the standard code to reverse a number.(This code is used in C language,of course,according to its own syntax!)Also,it is easy to understand.Remember this code,I think it is very helpful!
a = 126986;
b = a; % Save value of "a" in new variable "b".
reverse = 0;
while b > 0 % OR while b ~= 0 (Both 'while' statements are same.)
r = rem(b,10);
reverse = reverse * 10 + r;
b = floor(b/10);
end
a
reverse

Joshua Amuga on 2 Nov 2016
IVP :=ode({y''(x)+4*y'(x)+3*y,y(0)=3,y'(0)=4},y(x)); Undefined function or variable 'IVP'. this is what i got