I'm learning Python, and I'm having trouble with this simple piece of code:
a = raw_input('Enter a number: ')
if a > 0:
print 'Positive'
elif a == 0:
print 'Null'
elif a < 0:
print 'Negative'
It works great, apart from the fact that it always prints 'Positive', no matter if i enter a positive or negative number or zero. I'm guessing there's a simple solution, but i can't find it ;-)
Thanks in advance
Because you are using raw_input you are getting the value as a String, which is always considered greater than 0 (even if the String is '-10')
Instead, try using input('Enter a number: ') and python will do the type conversion for you.
The final code would look like this:
a = input('Enter a number: ')
if a > 0:
print 'Positive'
elif a == 0:
print 'Null'
elif a < 0:
print 'Negative'
However, as a number of folks have pointed out, using input() may lead to an error because it actually interprets the python objects passed in.
A safer way to handle this can be to cast raw_input with the desired type, as in:
a = int( raw_input('Enter a number: '))
But beware, you will still need to do some error handling here to avoid trouble!
input is not safe. Try using a = int(raw_input('Enter:')) insteadThat's because a is a string as inputted. Use int() to convert it to an integer before doing numeric comparisons.
a = int(raw_input('Enter a number: '))
if a > 0:
print 'Positive'
elif a == 0:
print 'Null'
elif a < 0:
print 'Negative'
Alternatively, input() will do type conversion for you.
a = input('Enter a number: ')
Expanding on my comment on the accepted answer, here's how I would do it.
value = None
getting_input = True
while getting_input:
try:
value = int(raw_input('Gimme a number: '))
getting_input = False
except ValueError:
print "That's not a number... try again."
if value > 0:
print 'Positive'
elif value < 0:
print 'Negative'
else:
print 'Null'
raw_input
returns a string so you need to convert a which is a string to an integer first: a = int(a)
raw_input is stored as a string, not an integer.
Try using a = int(a) before performing comparisons.
raw input will return a string, not an integer. To convert it, try adding this line immediately after your raw_input statement:
a = int(a)
This will convert the string to an integer. You can crash it by giving it non-numeric data, though, so be careful.
