An interactive introduction to MATLAB

62 loops

• Lines 3–4 contain the body of the loop, in this case the value of the loop
  counter variablexis printed. Then the value ofxis incremented by 1.
  The value ofxmust be explicitly incremented otherwisexwill always
  be equal to 1, the conditionx<10will always be true, and the loop will
  therefore execute continuously.


• Lines 6–23 contain the results of running thewhileloop.

Breaking out of a loop

If you end up stuck in an infinitely repeating loop use CTRL + C to force

MATLABto break out of the loop. However, under certain conditions you

may want your code to break out of a loop before it is finished. To do this

you can use thebreakcommand. Statements in your loop after thebreak

command will not be executed.

The while loop

(http://www.eng.ed.ac.uk/teaching/courses/matlab/unit05/while-

loop.shtml)

Self Test Exercise: while loops

Evaluate the following expressions without usingMATLAB. Check your an-

swers withMATLAB.

1. How many times will this code printHello World?
   1 n = 10;
   2 while n > 0
   3 disp('Hello World')
   4 n = n−1;
   5 end


2. How many times will this code printHello World?
   1 n = 1;
   2 while n > 0
   3 disp('Hello World')
   4 n = n + 1;
   5 end


3. What values will this code print?
   1 a = 1
   2 while a < 100
   3 a = a* 2
   4 end