This code will raise NameError: name 'i' is not defined:
for n in range(2, 101):
for i in range(2, n):
if n % i == 0:
break
if n % i != 0:
print(n, end=' |')
This code will execute without error:
n = 97
if True:
for i in range(2, n):
if n % i == 0:
break
if n % i != 0:
print(n, end=' |')
Could anybody tell why?
When n is 2, range(2,n) will be an empty list, and so the body of that loop will not execute at all.
That has nothing to do with scopes, in fact for loops in python do not create their own scopes unless it is in a list comprehension. The reason you are getting an error is i is not getting created in the first code.
for n in range(2,101):
# at first iteration n == 2
for i in range(2,n):
# this is equivalent to range(2,2) in first iteration
So, there is nothing to iterate on, hence no value is assigned to i. And when it goes to n % i, it throws NameError.
In the second block:
for i in range(2, n):
# value if i is 2
As i has a value, hence defined, it does not throw NameError.
