How to avoid using eval in this case

Question

Nico S 2016-1-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/263971-how-to-avoid-using-eval-in-this-case

评论： Star Strider 2016-1-16

Hello, im quite new in matlab. i already search a few topics about eval, but i cant find any useful topic for my problem ill just show the simple example, not the whole code

ex:

    % code
for subject = 1:22
for vid = 1:40
for i = 1:32
eval(sprintf('s%dmyvariable%d(%d,1) = YYY',subject,vid,i));
end
end
end

and it will generate: s1myvariable1 s1myvariable2 s1myvariable3 ... ... s1myvariable40 s2myvariable1 ... s22myvariable40

the code generates 880(22x40) dynamic variables name.. i use eval, and i have no problem so far except lots of variables in my workspace. But a few topics, well there's a lot of them actually, said that eval is evil, eval is not a friend, dont go near eval, youre gonna hurt yourself. but i cant find another alternatives.. can anyone help me please

2 个评论
显示无隐藏无

Image Analyst 2016-1-16

And how would you actually refer to or use those variables later if you don't know their names? Let's say that , for some reason, you wanted to use s13variable37. Would you say x=s13variable37? But what if that variable doesn't exist because subject and vid didn't go that high? You're better off using Star's solution, which is like the vast majority of programmers in any other language (which may not have eval) would do.

Nico S 2016-1-16