Using for loop to match generated random numbers to an input value

Question

Mark Coughlin 2020-4-28

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编辑： James Tursa 2020-4-28

Hi, I want to write a script which will prompt the user for minimum and maximum integers, and then another integer which is the user’s choice in the range from the minimum to the maximum. I then want the srcipt to generate random integers in the range from the minimum to the maximum until a match for the user’s choice is generated and print how many random integers had to be generated until a match for the user’s choice was found.

I am confused as to how to identify n, which is the number of iterations. Any suggestions would be greatly appreciated! This is my script so far:

function findmine
imin=input('Please enter your minimum value: ');
imax=input('Please enter your maximum value: ');
choice=input('Now enter your choice in this range: ');
% n=number of attempts
for i=1:n
    x(i)=randi([imin imax]);
    if x(i)==choice
        formatSpec='It took %d tries to get your number\n';
        fprintf(formatSpec,n);
    else
    end
end
end

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Answer 1

James Tursa 2020-4-28

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编辑：James Tursa 2020-4-28

在 MATLAB Online 中打开

Since you don't know ahead of time how many tries it will take, this is best done with a while loop instead of a for loop. E.g.,

n = 0;
while( true )
    x=randi([imin imax]);
    n = n + 1;

And when you get a match, use a break statement to get out of the while loop.

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Answer 2

Steven Lord 2020-4-28

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You have no control over how many iterations it will take to match the number the user chose, so a for loop (which has an upper bound that is set when you enter the loop on how many iterations it can run) is not the best choice of a control structure in this case.

A while loop doesn't have such an inherent upper bound, so I'd use that instead.

You probably also want to validate the user's inputs. randi can only generate integer values, so what if the user chose to enter 1.5 as their choice? What if they chose 42 as their number "in the range" 1 to 10?