For loop execution in Python

Question

I am new to python and just in the initial phase of the basics. Can someone please explain me how the for loop in the below code works? and I really don't get how number 9 is getting 3 as inner value.

Kindly tell me how the loops executes. TIA.

CODE:

for outer in range(2,10):
    for inner in range(2,outer):
        if not outer%inner:
            print(outer,'=',inner,'*',int(outer/inner))
            break   
    else:
        print(outer,'is prime')

Output:
2 is prime
3 is prime
4 = 2 * 2
5 is prime
6 = 2 * 3
7 is prime
8 = 2 * 4
9 = 3 * 3

Saeed · Accepted Answer · 2020-01-03 18:53:15Z

1

The inner loop runs multiple times for each execution of outer loop.

For value of 9 of outer loop, the inner loop executes from 2 to outer value.

answered Jan 3, 2020 at 18:53

Saeed

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Comments

Libra · Accepted Answer · 2020-01-03 18:59:19Z

1

I commented your code below, It should explain what is going on.

# This loop loops through numbers 2-9, and assigns them to the variable 'outer'
for outer in range(2,10):
    # This loop loops through numbers 2-(outer-1), and assigns them to the variable 'inner'
    for inner in range(2,outer):
        # if outer % inner == 0, the code is executed
        if not outer%inner:
            # When this is executed for 9, it will print 9 = 3 * 3
            print(outer,'=',inner,'*',int(outer/inner))
            break   
    else:
        print(outer,'is prime')

edited Jan 3, 2020 at 18:59

answered Jan 3, 2020 at 18:55

Libra

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1 Comment

marxmacher Over a year ago

first comment loops through 2-9 and assigns them to variable would be correct

John Brandli · Accepted Answer · 2020-01-03 18:51:12Z

0

Your inner loop executes multiple times for every one execution of the outer loop.

For an outer value of 9 your inner loop will execute from 2 to (outer) which is 9.

answered Jan 3, 2020 at 18:51

John Brandli

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