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I was using pop function to catch a value and then add them as below

my_list = [1,2,3,4,5]  
a = my_list.pop(0)
b = my_list.pop(0)
c = a+b
print(c)

I was expecting the output as 2 but it shows it as 3. I tried capturing value at different position and add them but it always gave me a number higher then the actual answer

like if POP position were 1 and 2 the addition should be 5 but it shows 6.

Can someone help me with more clarity on this please?

I was using pop function to catch a value and then add them as below

my_list = [1,2,3,4,5]  
a = my_list.pop(0)
b = my_list.pop(0)
c = a+b
print(c)

I was expecting the output as 2 but it shows it as 3. I tried capturing value at different position and add them but it always gave me a number higher then the actual answer

like if POP position were 1 and 2 the addition should be 5 but it shows 6.

Can someone help me with more clarity on this please?

• python
• list

Share Improve this question Follow edited Mar 27 at 21:09 Timur Shtatland 12.4k33 gold badges3838 silver badges6464 bronze badges asked Mar 27 at 20:50 mindbuzzzmindbuzzz 2111 silver badge11 bronze badge 1

• It helps to break the problem into smaller parts. You could introduce a print() after every line to see what the last line returned and what's in my_list. This way, you could quickly single out which line surprises you. – Friedrich Commented Mar 27 at 21:10

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1 Answer 1

Sorted by: Reset to default 3

I was expecting the output as 2 but it shows it as 3.

Keep in mind that pop() removes the element from the list. (At the specified index, which is 0 here.) So when you do this:

my_list = [1,2,3,4,5]
a = my_list.pop(0)

The a variable now has a value of 1. But my_list is now [2,3,4,5]. So when you do this:

b = my_list.pop(0)

Then b will have a value of 2, and now my_list will be [3,4,5].

The code is working correctly, the list is simply changing as it goes.

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To achieve the behavior you're expecting, don't use pop(). Just reference the element in the list:

my_list = [1,2,3,4,5]  
a = my_list[0]
b = my_list[0]
c = a+b
print(c)

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You can learn more about lists in Python here.

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