CODEWITHSUNDEEP
pythonpython-2.7if-statementmodulo
Anonamous
Anonamous

Reputation: 303

If statement with modulo operator

I tried this -

x=[2,3,4,7,9]
count=0
for i in x:
  if i%2:
    count=count+1
print count

why the count is 3 instead of 2, as i%2 is satusfiying only for "2 and 4"?

Upvotes: 6

Views: 51179

Answers (3)

Harsha Biyani
Harsha Biyani

Reputation: 7268

If the Boolean expression evaluates to true(it can be any non zero value), then the if block will be executed.

You can achieve to get all even number counts by updating code as follows :

x=[2,3,4,7,9]
count=0
for i in x:
  if i%2 == 0 :
    count=count+1
print count

Upvotes: 1

Daachi
Daachi

Reputation: 173

Why you are having this problem is because you have signed told your code what to expect when your if statement meets a condition. As pointed out by @Harsha, to satisfy the condition for even numbers, it should be:

x=[2,3,4,7,9]
count=0
for i in x:
  if i%2 = 0:
    count=count+1
print count

If you want to get the odd numbers:

x=[2,3,4,7,9]
count=0
for i in x:
  if i%2 > 0 :
    count=count+1
print count

Upvotes: 0

Martijn Pieters
Martijn Pieters

Reputation: 1122372

The modulus of 2 over 2 is zero:

>>> 2 % 2
0

So 2 % 2 produces 0, which is a false value, and thus the if statement doesn't match.

On the other hand, the modulus of 3 over to is one:

>>> 3 % 2
1

1 is a non-zero integer, so considered true.

In other words, the if i%2: test matches odd numbers, not even. There are 3 odd numbers in your list.

Remember, modulus gives you the remainder of a division. 2 and 4 can be cleanly divided by 2, so there is no remainder. The if test checks for a remainder.

Upvotes: 4

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