Getting out of multiple for loops in MATLAB - matlab

Question

I have a homework exercise that asks for a script that finds smallest 3-digit Armstrong Number.
I wrote my script. It works fine for finding these numbers, but I don’t know how to stop at first Armstrong number.
Here is my code
a=0;
b=0;
c=0;
for x1=1:1:9
a=x1^3;
for x2=0:1:9
b=x2^3;
for x3=0:1:9
c=x3^3;
d=(x1*100 + x2*10 + x3);
if (a+b+c) == (d)
disp(d)
end
end
end
end
It normally prints 153 370 371 407.
If I use break after disp it just gets out of first for and not all, and prints 153 370 407.

Answer 1

You can stop loops with the keyword break. However, this just stops one loop. You have now to options
set some kind of flag and check it in every loop to terminate (break) it (aka: the proper way)
use return (aka: the nasty way)
Option 1
a = 0;
b = 0;
c = 0;
FLAG_STOP = false;
for x1 = 1:9
a = x1^3;
for x2 = 0:9
b = x2^3;
for x3 = 0:9
c = x3^3;
d = (x1*100 + x2*10 + x3);
if (a+b+c) == (d)
disp(d)
% set flag
FLAG_STOP = true;
break
end
end
if FLAG_STOP
break
end
end
if FLAG_STOP
break
end
end
Option 2
a word of warning:
(...) it does not just exit the loop; it exits the script or function and
returns control to the invoking program or command prompt.
i.e. all statements after return will be ignored -- with no matter whether they are part of a loop or not
a = 0;
b = 0;
c = 0;
for x1 = 1:9
a = x1^3;
for x2 = 0:9
b = x2^3;
for x3 = 0:9
c = x3^3;
d = (x1*100 + x2*10 + x3);
if (a+b+c) == (d)
disp(d)
return % <<<<<<<<<<<<
end
end
end
end

Answer 2

If you don't want to use return as recommended in #max's answer you may use try/catch and error to handle such cases:
try
a = 0;
b = 0;
c = 0;
for x1 = 1:9
a = x1^3;
for x2 = 0:9
b = x2^3;
for x3 = 0:9
c = x3^3;
d = (x1*100 + x2*10 + x3);
if (a+b+c) == (d)
disp(d)
error("") ;
end
end
end
end
catch
end