Prompt the user for a number and check whether it is prime or not. Collect these prime numbers and write it to an output text file.

1. Define a variable continue_flag to use in the while loop
2. Also, create an empty vector called prime_numbers
3. In the while loop, prompt the user for an integer input and determine whether it is a prime number or not
4. Update the vector prime_numbers accordingly
5. Also, prompt the user to continue or terminate the session and update the continue_flag variable accordingly
6. Write the prime_numbers to an output file called prime_numbers_output.txt or a file of choice

[Daniel Neubauer]

this looks like a homework problem, mybe try writing the code up to the point you can and then ask a specific question where you are stuck!

[Sagar]

c_flag=1;
prime_numbers = [];
while (c_flag==1)
    x = input('Enter Number: ');
    if isprime (x) == 1
        disp (['x is a prime number with value: ',num2str(x)]);
    else
        disp (['x is not a prime number with value: ',num2str(x)]);
    end
    c_flag=input('Enter 1 to continue or 0 to terminate: '); 
end
writematrix(prime_numbers,'prime_numbers_op.txt')

[Sagar]

Mr. Daniel Neubauer

The above program i've written is working but in last, all the prime numbers are not saving in output text file

Answer 1

[Jan]

Your code does not collect the prime numbers. Add this in the branch, where a prime number is identified:

prime_numbers = [prime_numbers, x];

or

prime_numbers(end + 1) = x;

By the way, you do not have to compare a logical values by ==1 to convert it to a logical value. This is enough alreaedy:

if isprime(x)
    ...
end

Answer 2

[Image Analyst]

@Sagar some improvements to your code are below:

prime_numbers = [];
loopCounter = 1;
maxIterations = 20;
x = 1;
while (x ~= 0) && loopCounter < maxIterations
    x = input('Enter Number (0 to terminate) : ');
    prime_numbers(loopCounter) = x;
    loopCounter = loopCounter + 1;
    if isprime(x) == 1
        disp (['x is a prime number with value: ',num2str(x)]);
    else
        disp (['x is not a prime number with value: ',num2str(x)]);
    end
end
writematrix(prime_numbers,'prime_numbers_op.txt')
winopen('prime_numbers_op.txt')