What am I not seeing here

Here is a small script that I wrote after I missed a colon and saw some unexpected (by me) behavior in some work I was doing.

clc;
a=10;
for i=1length(a) % yes, it is i=<digit 1><no space><length(a)>
   disp(i) 
end

Yes, I know I am missing the colon in the for loop line, but that is exactly my point. I get this output at the command prompt,

ans =

     1

     1

but I am expecting an error

??? 1length(a)
   |
Error: Unexpected MATLAB expression.

I know I am not able to see something, probably something silly, obvious and embarrassing, but I just don't know what. Would like somebody to help me out here, thanks in advance.

[Jan]

5 votes in 22 minutes - this is the current record here. You've written my "post of the week".

Answer 1

[Matt Fig]

You are seeing the print out of length(a) then disp(i). I am thinking that this is a bug, or the parser is supposed to be so smart as to not let you error here. It certainly is unexpected!

I could see the parser recognizing a function call, but this works too:

a = 10;
for i = 7a 
   disp(i) 
end

M-Lint underlines the a and says, "Use newline, semicolon or comma before this statement." So it is just a smart parser!

This works for more that FOR loops!

a = 10;
if 2a,end

and also,

while a==10a,end  % ctrl+c ahead!

Answer 2

[Jan]

Even in the command window of the ancient Matlab 6.5:

a = 10:12;
for i=2length(a), disp(8); end

 >> ans =
          3
          8
 >> disp(i)
    i = 2

Strange. The parser seems to be lazy:

for i=2sin(1:4), end
>> ans = 0.8415  0.9093  0.1411 -0.7568

[Paulo Silva]

Never seen such weird behavior, very interesting!