Creating a loop with an empty Matrix

I'm working on a code that requires me to replace the values in an empty matrix with new ones. I'm trying to do this using a while loop but can't seem to get it right can anyone provide some insight as to how I should continue? I was thinking something along the lines of this:

M=zeroes(5)
while M 'contains a zero'
    x=randi(5)
    Y=randi(5)
    M(x,y)='Replavement Value Function'
end

This issue I'm having is I don't understand how to write the while loop such that it will continuously perform this operation until M no longer contains a zero.

Answer 1

[Guillaume]

Note: an empty matrix (a matrix whose any dimension is of size 0) and a matrix filled with 0s are two completely different things.

Prior to R2018b, use

while any(M(:) == 0)

to check if any element of M is equal to 0. In R2018b, you can use

while any(M == 0, 'all')

to do the same

[William Diaz]

Thanks this is what I was looking for! Quick follow up is their a way to track the number of times it has to perform the loop before all the values are replaced?

[Guillaume]

Use a counter incremented inside the loop:

counter = 0;
while any(M == 0, 'all')
    counter = counter+1;
    %...
end

[William Diaz]

Perfect thank you