William Becerra wrote:
> Hey, I'm new to programming
> running Python 2.7.8 Windows 8.1
> I was reading 'How to Think Like a Computer Scientist- Learning with
> Python' chapter 7 sub-chapter 7.7
>
> I have the following code:
> names = "John, Cindy, Peter"
> def find(str, ch, s):
> index = 0
> while index < len(str):
> if s==1:
> for char in names[:4]:
> if str[index] == ch:
> return index + 1
> index = index + 1
> if s==2:
> for char in names[6:11]:
> if str[index] == ch:
> return index + 1
> index = index + 1
> if s==3:
> for char in names[13:]:
> if str[index] == ch:
> return index + 1
> index = index + 1
> return -1
> print find(names,"n", 2)
>
>
>
> and my problem is:
> I intend for the parameter s to tell the interpreter which name to look at
> so that i get the index return value related to that name.
> for example:
> John and Cindy both have a letter 'n' but when I call the function
> with an s value of 2 I want it to return the index value of the letter n
> in Cindy and not in John.
>
> Can Someone Please tell me why my code isn't working like I intend it to?
> Thank you
While Python has ready-to-use solutions for the subproblems of what you are
trying to do, solving the problem by hand is still a good learning
experience. But you are trying to do too much at the same time.
Can you write a function that finds a char in one name?
Once you have that -- let's call it find_char() -- you can rewrite your
find() as
def find(names, ch, name_index):
if name_index == 1:
name = names[:4]
elif name_index == 2:
name = names[6:11]
elif name_index == 3:
name = names[13:]
else:
# if you know about exceptions raise a ValueError instead
# of printing the error message
print "ERROR: name_index must be 1, 2, or 3"
return None
return find_char(name, ch)
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