How to properly iterate through a for loop with python

Question

I am relatively inexperienced and come from c#. I am attempting to iterate through a string and individually print out each letter using a for loop.

In c# this would (if I remember correctly) be written like so:

 string x = test;
 foreach(i in x)
 {
  print(x[i]);
 }

But in python, when I type

  x = "test"
  for i in x:
    print(x[i])

The python shell tells me that i must be an integer.

I am actually pretty sure that my syntax is incorrect in my c# example, but to get to the question:

How would i properly iterate through a string using a for, or foreach loop in Python?

I have been searching the web and am somehow coming up empty handed. Sorry if this is a foolish inquiry.

for i in x grabs each character in x. Indexing with x[i] won't work because you're using a character for the index. Change it to for i in range(len(x)) to get it working correctly. — Dimitris Fasarakis Hilliard
– Dimitris Fasarakis Hilliard, Commented Jun 9, 2016 at 21:00
"In c# this would (if I remember correctly) be written like so" - you remember wrong. C# foreach goes over elements rather than indices, just like Python. — user2357112
– user2357112, Commented Jun 9, 2016 at 21:01
@user2357112 Yes I realize now after looking at previous practice I had done, thank you — spoon_man
– spoon_man, Commented Jun 9, 2016 at 22:31
@Jim I didn't even think to use len() for something like this, thanks for that! — spoon_man
– spoon_man, Commented Jun 9, 2016 at 22:31

Rick · Accepted Answer · 2016-06-09 22:01:22Z

1

Your variable x is a string type, therefore, when you type x[i] you are going to get the letter at the position i.

However, in your loop, you have something different:

x = "test"
for i in x:
    print(x[i])

This for loop (for i in x) means: for each letter i in the string x, do the following. So, your i variable is actually a letter, not an integer.

So, to print every letter of the string x, just use print(i):

x = "test"
for i in x:
    print(i)

But, if you really want your i to be an integer, instead of for i in x, use for i in range(0, len(x)). And in this case, you would have to access the letter by using what you originally wrote (x[i]).

x = "test"
for i in range(0, len(x)):
    print(x[i])

answered Jun 9, 2016 at 22:01

Rick

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spoon_man Over a year ago

Thanks! That was very indepth and covered everything I had concerns about.

nekomatic · Accepted Answer · 2016-06-09 21:07:43Z

0

If you really want a loop index for some reason, you can use enumerate:

x = 'test'
for i, c in enumerate(x):
    print(i, x[i], c)

answered Jun 9, 2016 at 21:07

nekomatic

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Comments

Arete · Accepted Answer · 2016-06-09 21:27:04Z

0

This took me a bit to understand as well, but I think I understand the misunderstanding. The i in for i in x already refers to the character, not the index. For example, writing

stringx='hello world for i in stringx: print stringx[i] is the same as writing

print stringx['h']

answered Jun 9, 2016 at 21:27

Arete

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