3.7 BREAK指令

break這一個指令常與迴圈while 或for 配合使用，可以自迴圈中跳出至上一層之迴圈，在巢狀迴圈中，break僅能自最內圈跳出圈外，到其對應之end後繼續執行。下面之範例配合while 1…end執行輸入的問答，只有回答Ｎ才能利用break跳出迴圈。

% Using break to terminate the execttion.
n=1;
while 1
    a=input('Continue? (Y/N) ','s');
    A=upper(a);
    if isempty(A), A='Y';end
    if A=='N', break; end
    if A=='Y',
       disp('OK, you know how to use BREAK, don''t you?')
       disp(['You just try ',int2str(n),' time(s)! Do it again.'])
       n=n+1;
    else
       disp('I don''t understand, please input again.')
    end
end

執行之結果：

>>show_break
Continue? (Y/N) d
I don't understand, please input again.
Continue? (Y/N) y
OK, you know how to use BREAK, don't you?
You just try 1 time(s)! Do it again.
Continue? (Y/N) y
OK, you know how to use BREAK, don't you?
You just try 2 time(s)! Do it again.
Continue? (Y/N) n