if loop error in MALAB

Question

ali hassan 2022-2-2

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https://ww2.mathworks.cn/matlabcentral/answers/1641240-if-loop-error-in-malab

评论： Steven Lord 2022-2-2

i am using the following if loop but it is not executing:

n=[]
if n==[]
    sprintf('a')
end

it dose not print 'a'

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ali hassan 2022-2-2

编辑：ali hassan 2022-2-2

but why it is not working that way?@James Tursa

Steven Lord 2022-2-2

在 MATLAB Online 中打开

From the documentation page: "if expression, statements, end evaluates an expression, and executes a group of statements when the expression is true. An expression is true when its result is nonempty and contains only nonzero elements (logical or real numeric). Otherwise, the expression is false."

Is your expression nonempty and does it contain only nonzero elements?

n = [];

n == []

ans = 0×0 empty logical array

Your expression is empty so the statements inside the if block are not executed.

If you look at the suggestion from James Tursa:

isempty(n)
ans = logical
   1

This is nonempty and it contains only nonzero elements. Therefore the if statement's expression is true and so the statements inside the if block are executed.

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