For and While Loops

Question	Click to View Answer
What does the following print to the console. sum = 0 counter = 0 numbers = [1, 2, 3, 4] while counter < len(numbers): sum = sum + numbers[counter] counter = counter + 1 print(sum)	`10` is printed. The `sum` and `counter` variables are initially set to zero. The `while` loop is used to iterate over every item in the `numbers` list and update the `sum` variable. The `counter` variable is incremented for each loop iteration.
What does the following print to the console. word = "" counter = 0 letters = ["c", "a", "r"] while counter < len(letters): word = word + letters[counter] counter = counter + 1 print(word)	`"car"` is printed. The `word` variable is initially set to the empty string and a `while` loop is used to iterate over every item in the `letters` list. Each letter is appended to the `word` variable and the `counter` is incremented for each loop iteration.
What does the following print to the console. sum = 0 counter = 0 numbers = [22, 55, 111, 555] while numbers[counter] < 100: sum = sum + numbers[counter] counter = counter + 1 print(sum)	`77` is printed. This `while` loop sums all the numbers in the list until it hits a number that's greater than 100. In this example, the loop sums `22` and `55` and then exits when it hits `111`.
What does the following print to the console. result = 0 numbers = [2, 4, 6] for num in numbers: result = result + num print(result)	`12` is printed. The `for` loop iterates over every element in the `numbers` list and sums them in the `result` variable. `for` loops are similar to `while` loops, but they allow for less typing because counter variables aren't needed.
What does the following print to the console. word = "" letters = ["t", "r", "a", "i", "n"] for letter in letters: word = word + letter print(word)	`"train"` is printed. The `for` loop iterates over ever letter in the `letters` list and appends each letter to the `word` variable. The resulting string is then printed.