like this:
def pullchar(s):
"""pull a single character from the front of a string"""
c = s[0]
s = s[1::]
return c
Can python do this? Not really...
Why? Because there doesn't seem to be any way to pass a variable to a function...
WTF?
Tuesday, March 18, 2008
Python sucks!
All I want to do is to take a string, and pull the first character off of it in a function....
like this:
Can python do this? Not really...
Why? Because there doesn't seem to be any way to pass a variable to a function...
WTF?
like this:
Can python do this? Not really...
Why? Because there doesn't seem to be any way to pass a variable to a function...
WTF?
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6 comments:
You don't really need a function for a simple operation like this, as Python's language conventions can handle it just fine:
c, s = s[0], s[1:]
Adding a new function to do this may make your code more complicated. Of course, you might want a check to see if the string has a length of 2 or more, and so then a function would be good:
def pullchar(s):
if len(s) >= 2:
return s[0], s[1:]
elif len(s) == 1:
return s, ''
else:
return '', ''
c, s = pullchar(s)
You seem to be miffed that Python does not pass by reference for strings, but this is because Python has string immutability. String immutability is a design decision that makes a lot of sense for performance and multithreaded apps.
Of course, Python lets you convert an immutable string into a mutable list very easily:
s = 'Hello world!'
s = list(s)
Then you could pass this list of single characters by reference. But doing all of that doesn't improve performance or productivity. I think either of the two solutions is fine.
Are you sure you don't want to just iterate over all characters in the string?
mystring = 'foo'
for character in mystring:
do_something(character)
Also, in your other post ("Python Rocks!") you mention you are trying to use this to process data files. In that case you might want to do something like:
f = open('hugin.pto', 'rb') # the 'b' is for binary mode, may not be necessary for your data
character = f.read(1)
while character:
do_something(character)
character = f.read(1)
Or:
>>> string = "abcdefgh"
>>> stack = list(string)
>>> stack.reverse()
Now, each time you want to pull one character out, you do:
>>> stack.pop()
'a'
>>> stack.pop()
'b'
>>> stack.pop()
'c'
>>> stack.pop()
'd'
etc.
Do you know why Python _really_ sucks? It has string immutability, but it doesn't compensate for this by giving you good tools for doing functional programming on strings. There's no string.reverse(), for example.
In [1]: s = 'toast'
In [2]: s[::-1]
Out[2]: 'tsaot'
It is way easier to understand string.reverse() than s[::-1] - python sucks
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