Please explain how this program works ^_^::

Question

def func(x):
res = 0
for i in range(x):
res += i
return res

print(func(4))

Answer 1

Pretty margaret

Look at it this way ::
================

def func(x):
defines a function func()
that takes in an argument "x";

next :: res =0;
declares a variable "res" and sets it to 0

for i in range(x):
declares a for loop, using "i" as the control variable.
Here, i starts at 0 and increases by 1,till it gets to (x-1), which in this case is (4-1).

Note::: i stops at x-1, not x.

So the range becomes
0,1,2,3

next :: red +=i ;
each time the loop runs, the value of "i" gets added to "res".

so if you call func(4),

it is the same as saying
i =0
res +=0; res= 0

i=1
res +=1; res= 1

i=2
red +=2; res =3

i=3
res += 3; res=6

Answer 2

Make sure you indent your code blocks after the colons or it won't work 😉

def func(x):
res = 0
for i in range(x):
res += i
return res

print(func(4))