Variable Not fully defined on some execution path error

Question

John Petersen 2021-3-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/770148-variable-not-fully-defined-on-some-execution-path-error

评论： John Petersen 2021-3-11

I have some code that is inside a simulink block that gets an error when it's compiled. It says a variable is not fully defined on some execution paths, but it's not true.

Here's a simplified version of the code:

function myfunc(logicA, logicB)
A = logicA;
B = logicB;  % also input from the function
if A
    X = 1;
elseif B
    X = 2;
end
if (A || B)
    Y = X;
end

It complies fine if I change it to

function myfunc(logicA, logicB)
A = logicA;
B = logicB;  % also input from the function
X=2
if A
    X = 1;
end
if (A || B)
    Y = X;
end

It looks like the compiler doesn't realize that it doesn't need X if (A || B) is false?

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Answer 1

Walter Roberson 2021-3-11

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/770148-variable-not-fully-defined-on-some-execution-path-error#answer_645428

在 MATLAB Online 中打开

disp(myfunc(1,1))
     1
disp(myfunc(1,0))
     1
disp(myfunc(0,1))
     2
disp(myfunc(0,0))
Output argument "Y" (and maybe others) not assigned during call to "solution>myfunc".
function Y = myfunc(logicA, logicB)
A = logicA;
B = logicB;  % also input from the function
if A
    X = 1;
elseif B
    X = 2;
end
if (A || B)
    Y = X;
end
end