If statement not working correctly

2016 8 3
1 个回答
回答已采纳
更新时间：2016 8 4
6 次查看（30 天）

0 个投票

This is driving me insane, I've checked the code 101 times yet can't find any error. This a simple application of if statement.
for i=1:c
parity=mod(x(i),2);
d=bistr(i);
if parity==1 && d==0
display('Hello');
elseif parity==0 && d==0
display('How');
elseif parity==0 && d==1
display('Are');
elseif parity==1 && d==1
display('You');
end
end
i goes from 1 to 192 (c=192). As you can see, parity can either be 0 or 1. d is also either 0 or 1 (it's a matrix of 1s and 0s)
YET THIS CODE WON'T PRINT ANY SINGLE OF THE STRING 'HELLO','HOW','ARE' or 'YOU'. Like I've exhausted all the logical possibilities for parity and d. What is going wrong?
(Yes I've tried printing every single variable at the starting of the loop to see if the loop itself is working fine. IT IS. IT'S JUST THAT THE IF STATEMENT ISN'T GETTING EXECUTED AT ALL!)

3 个评论
显示 1更早的评论 隐藏 1更早的评论

Stephen23
Stephen23 2016-8-3
编辑：Stephen23 2016-8-3
"If statement not working correctly"
Yes, it is. You are not providing values that fulfill those conditions. This is not if's fault.
You have not told us what x is, but if it is floating point and contains any small fractional values then the equivalence statements will always be false. Note that MATLAB will not display small fractional part for an integer, unless you change the format:
>> 1.0000000000006
ans = 1.0000
>> format longg
>> 1.0000000000006
ans = 1.0000000000006
Also the name bistr indicates that it is a string: note that the string '1' does not have a value of one!:
>> double('1')
ans = 49
Please tell us how you are generating x and bistr, and also upload examples of these variables in one mat file (change file extension to txt) by clicking the paperclip button.
Adam
Adam 2016-8-3
What is 'bistr'?
Presumably whatever it is returning is not actually either a 0 or a 1
Arnav Barbaad
Arnav Barbaad 2016-8-3
You are right Adam, bistr is returning '1' instead of 1

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Steven Lord
Steven Lord 2016-8-3

0 个投票

Look at the classes of parity and d. My guess is that parity is a double array but d (being an element of an array I assume is called "bitstr" not "bistr") is a char array.
'1' == 1 % returns false
true == 1 % returns true
1 == 1 % returns true
So if d is a char array, bitstr will look something like:
>> bitstr = char(randi(double('01'), 4, 4))
bitstr =
0111
1010
1111
1100
The elements of bitstr are not equal to 0 or 1 but are equal to either '0' or '1'.
>> bitstr == '1'

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Arnav Barbaad
Arnav Barbaad 2016-8-3
Omg you're bang on spot. I was wondering why my bistr matrix is so compact while other matrices are more spread out. It's because bistr is a char array. (binary string=bistr, hehhe)
bistr looks exactly like you've mentioned (just that I'm using 8 bit binary numbers, so every row contains 8 0s or 1s)
How do you I convert it from a char matrix to a int matrix?
Arnav Barbaad
Arnav Barbaad 2016-8-3
Also, is it because I'm using dec2bin instead of de2bi for defining bistr matrix?
de2bi is not working on my mac (it was working on windows)
de2bi returns the following:- >> de2bi(4) Undefined function 'de2bi' for input arguments of type 'double'.
(No matter what argument type I put it, it always returns the same error)
Arnav Barbaad
Arnav Barbaad 2016-8-3
Well got it. The windows belonged to my professor who had a full version license. Since de2bi belongs to communication system toolbox, my student license MATLAB doesn't have it. Hence the error
Steven Lord
Steven Lord 2016-8-4
You could use '1' instead of 1 in your if statement, or subtract '0' from the array (since '0' and '1' are adjacent in ASCII), or convert to logical using:
bistr == '1'

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Logical 的更多信息

产品

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by