How Would I Stop a While Loop After N Amount of Time

How would I stop a while loop after n amount of time?

Try the following:

import time
timeout = time.time() + 60*5   # 5 minutes from now
while True:
    test = 0
    if test == 5 or time.time() > timeout:
        break
    test = test - 1

You may also want to add a short sleep here so this loop is not hogging CPU (for example time.sleep(1) at the beginning or end of the loop body).

How to stop a while loop after n iterations?

The short answer is that you need to add a n += 1 in the while loops, like that:

def easy_level():
  n= 0
  while n < 10:
    user_number=int(input('Guess the number: '))
    if user_number > number:
      print('Too high')
    elif user_number < number:
      print('Too low')
    elif user_number == number:
      print(f'You guessed the number {number}! Congratulations!')
      play_again=input('Would you like to play again? type y for yes or n for no: ')
      if play_again =='y':
        levels()
      else:
        print('Bye')
         break

    n += 1

  print('Sorry, no more attempts :(')

Long answer is that you should really consider using a for loop instead, here is an example of how you can do that:

def easy_level():
  for i in range(10)
    user_number=int(input('Guess the number: '))
    if user_number > number:
      print('Too high')
    elif user_number < number:
      print('Too low')
    elif user_number == number:
      print(f'You guessed the number {number}! Congratulations!')
      play_again=input('Would you like to play again? type y for yes or n for no: ')
      if play_again =='y':
        levels()
      else:
        print('Bye')
         break

  print('Sorry, no more attempts :(')

And you should make your script a lot cleaner by removing the repetitive code like this:

from random import *

def chooseLevel():
  user_level=input('Type E for easy level and D for difficult level: ')
  if user_level=='e':
    return 10
  else:
    return 5

number = randint(1,100)
for i in range(chooseLevel()):
    user_number = int(input('Guess the number: '))
    if user_number > number:
      print('Too high')
    elif user_number < number:
      print('Too low')
    elif user_number == number:
      print(f'You guessed the number {number}! Congratulations!')
      play_again = input('Would you like to play again? type y for yes or n for no: ')
      if play_again =='y':
        levels()
      else:
        print('Bye')
         break

  print('Sorry, no more attempts :(')

Here I removed the two functions that you had and I made it so that there is only one loop which makes the code a lot cleaner, I also changed the levels() function name to chooseLevel() to make it clearer on what the function does and I also added spaces between the = which makes things look cleaner.

I also used the for loop like this for i in range(chooseLevel())
Which means that if the chooseLevel() function returned a 5 it will be as if I wrote for i in range(5) and if the chooseLevel() function returns a 10 it will be as if I wrote for i in range(10)

Thanks.

How to exit a while loop after a certain time?

long startTime = System.currentTimeMillis(); //fetch starting time
while(false||(System.currentTimeMillis()-startTime)<10000)
{
    // do something
}

Thus the statement

(System.currentTimeMillis()-startTime)<10000

Checks if it has been 10 seconds or 10,000 milliseconds since the loop started.

EDIT

As @Julien pointed out, this may fail if your code block inside the while loop takes a lot of time.Thus using ExecutorService would be a good option.

First we would have to implement Runnable

class MyTask implements Runnable
{
    public void run() { 
        // add your code here
    }
}

Then we can use ExecutorService like this,

ExecutorService executor = Executors.newSingleThreadExecutor();
executor.invokeAll(Arrays.asList(new MyTask()), 10, TimeUnit.SECONDS); // Timeout of 10 seconds.
executor.shutdown();

How do I escape while loop when I have N amount of inputs?

Maybe you are reading an input that has an EOF (End of file)?
In that case you should stop when receiving EOF

#include <stdio.h>
#include <ctype.h>

int main(void)
{
  int input;
  int i = 0;
  while (scanf("%d", &input) != EOF){
    printf("%d input:%d\n", i, input);
    i++;
  }
  printf("End\n");
  return 0;
}

Otherwise you can do a program that first reads N and then iterate N time

int main(void)
{
  int input;
  int i = 0;
  int n = 0;
  scanf("%d", &n);
  for (i = 0; i < n; i++) {
    scanf("%d", &input);
    printf("%d input:%d\n", i, input);
  }
  return 0;
}

For loop that breaks after n amount of seconds

By checking the elapsed time since the start:

var i int
for start := time.Now(); time.Since(start) < time.Second; {
    i++
}

Or using a "timeout" channel, acquired by calling time.After(). Use select to check if time is up, but you must add a default branch so it will be a non-blocking check. If time is up, break from the loop. Also very important to use a label and break from the for loop, else break will just break from the select and it will be an endless loop.

loop:
    for timeout := time.After(time.Second); ; {
        select {
        case <-timeout:
            break loop
        default:
        }
        i++
    }

Note: If the loop body also performs communication operations (like send or receive), using a timeout channel may be the only viable option! (You can list the timeout check and the loop's communication op in the same select.)

We may rewrite the timeout channel solution to not use a label:

for stay, timeout := true, time.After(time.Second); stay; {
    i++
    select {
    case <-timeout:
        stay = false
    default:
    }
}

Optimization

I know your loop is just an example, but if the loop is doing just a tiny bit of work, it is not worth checking the timeout in every iteration. We may rewrite the first solution to check timeout e.g. in every 10 iterations like this:

var i int
for start := time.Now(); ; {
    if i % 10 == 0 {
        if time.Since(start) > time.Second {
            break
        }
    }
    i++
}

We may choose an iteration number which is a multiple of 2, and then we may use bitmasks which is supposed to be even faster than remainder check:

var i int
for start := time.Now(); ; {
    if i&0x0f == 0 { // Check in every 16th iteration
        if time.Since(start) > time.Second {
            break
        }
    }
    i++
}

We may also calculate the end time once (when the loop must end), and then you just have to compare the current time to this:

var i int
for end := time.Now().Add(time.Second); ; {
    if i&0x0f == 0 { // Check in every 16th iteration
        if time.Now().After(end) {
            break
        }
    }
    i++
}

How to end a for loop after a given amount of time

You can do it with something like this:

import time

time_limit = 60 * 30 # Number of seconds in one minute
t0 = time.time()
for obj in list_of_objects_to_iterate_over:
    do_some_stuff(obj)   
    if time.time() - t0 > time_limit:
        break  

The break statement will exit the loop whenever the end of your iteration is reached after the time limit you have set.

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