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Don't understand while and for loops in python. Stuck
5 ответов
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I did this recently for some-one with a similar query.
See if it helps.
Extracted from Python tutorial, first lesson in 'for loops'
https://code.sololearn.com/cCrFrnVXYIxa/?ref=app
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For loops are basically loops that run a specific amount of times. Here's an example:
for num in range(0, 5): #this runs 6 times, because 0 is considered a time as well; num can be replaced with anything, it's just a placeholder for the number of times the for loop is running
print("Iteration " + str(num)) #as we said before, num contains the number the for loop currently is on, meaning this prints that
When we run this:
1st iteration: "Iteration 0"
2nd iteration: "Iteration 1"
3rd iteration: "Iteration 2"
4th iteration: "Iteration 3"
5th iteration: "Iteration 4"
6th iteration: "Iteration 5"
For loops can also be provided with a step, which creates a arithmetic sequence(2, 4, 6, 8...) Another use of for loops is to loop through a list, like this:
fruits = ["Apple", "Banana", "Orange"]
for fruit in fruits: #this will run each time for the number of items inside fruits, which is 3; fruit is a placeholder for the value of the item in the list
print("Fruit " + fruit)
Try this and see what happens.
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Continuing from my previous answer, we can now see the output:
Iteration 1: "Fruit Apple"
Iteration 2: "Fruit Banana"
Iteration 3: "Fruit Orange"
It basically iterates over every item in the list and prints it.
Now onto while loops. These loops basically run while a condition is true. For example, take the following while loop:
num = 0
while num < 7: #this runs again and again until num is greater than 10
print("Iteration " + str(num))
num += 1
When we run this, the result should be:
Iteration 1: "Iteration 0"
Iteration 2: "Iteration 1"
Iteration 3: "Iteration 2"
Iteration 4: "Iteration 3"
Iteration 5: "Iteration 4"
Iteration 6: "Iteration 5"
This basically does the same thing as the first for loop. But it's a different way of doing it.
Also, like Rik Wittkopp and HonFu have mentioned, check out the Python tutorial here for for and while loops.
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Then let me add the for part.
https://code.sololearn.com/cSdiWZr4Cdp7/?ref=app