Having trouble with string to float in python

Question

My goal is to create a program that will convert degrees to radians. The formula is (degrees * 3.14) / 180. But python keeps giving me this error:

Traceback (most recent call last):
  File "2.py", line 6, in <module>
    main()
  File "2.py", line 4, in main
    degrees = (degrees * 3.14) / 180
TypeError: can't multiply sequence by non-int of type 'float'

From this code:

def main():
    degrees = raw_input("Enter your degrees: ")
    float(degrees)
    degrees = (degrees * 3.14) / 180

main()

EDIT: Thank you all for the help!

DSM · Accepted Answer · 2012-04-01 01:27:30Z

8

float(degrees)

doesn't do anything. Or, rather, it makes a float from the string input degrees, but doesn't put it anywhere, so degrees stays a string. That's what the TypeError is saying: you're asking it to multiply a string by the number 3.14.

degrees = float(degrees)

would do it.

Incidentally, there are already functions to convert between degrees and radians in the math module:

>>> from math import degrees, radians, pi
>>> radians(45)
0.7853981633974483
>>> degrees(radians(45))
45.0
>>> degrees(pi/2)
90.0

answered Apr 1, 2012 at 1:27

DSM

355k67 gold badges606 silver badges504 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Zenon Over a year ago

I would just add that Strings are immutable in python thus all operations on them create a new object, never modify the original.

netbyte Over a year ago

Thanks!! Yeah, I know, but my teacher wants me to make a function for that myself.

Kristian Glass · Accepted Answer · 2012-04-01 01:28:55Z

2

float() doesn't modify its argument, it returns it as a float. I suspect what you want is (also adding standard __name__ convention out of habit):

def main():
    degrees = raw_input("Enter your degrees: ")
    degrees = float(degrees)
    degrees = (degrees * 3.14) / 180

if __name__ == '__main__':
    main()

answered Apr 1, 2012 at 1:28

Kristian Glass

38.7k7 gold badges50 silver badges74 bronze badges

2 Comments

netbyte Over a year ago

What does the if name == 'main': main() do?

Jeremy D Over a year ago

@netbyte check this out stackoverflow.com/questions/8228257/… :)

Collectives™ on Stack Overflow

Having trouble with string to float in python

2 Answers 2

2 Comments

2 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Linked

Related