Detecting a character one by one if it has a specific letter, then calculates the number of them

Question

I am trying to make a program that detects how many vowels are in a word you type. Here's my source code (I have multiple codes):

a = input("word - ").lower()
for i in range(1, len(a)+1):
  if a[str(i)] == "a" or "e" or "i" or "o" or "u":
    print("ok")
else:
  print("no")`

And I get the error:

TypeError: string indices must be integers

The second one:

a = input("word - ").lower()
for letter in a:
  if letter == "a" or "e" or "i" or "o" or "u":
    value = 0
    value = value + 1
print(value)

Also gives me an error:

TypeError: string indices must be integers

The third one is a little bit more complex:

a = input("rec - ").lower()
for i in range(1, len(a)+1):
  if a[str(i)] == "a":
    print("yes a")
  elif a[str(i)] == "e":
    print("yes e")
  elif a[str(i)] == "i":
    print("yes i")
  elif a[str(i)] == "o":
    print("yes o")
  elif a[str(i)] == "u":
    print("yes u")

I am working on Python 3.6.1 on Repl.it

You can check out the full source code at my profile.

I appreciate your help. Thank you!

Answer 1

In the first and last example you used a string as an index (a[str(i)]). However, indeces are always integers. And remember that the first index is always 0, not 1. Your for-loop iterates from 1. Since the first element has an index of 0, the last has an index of len(array) - 1, meaning, that your for-loop should only iterate to len(a). The problem with the for-loop index also applies to the last example.

In the second example you didn't use the or-statements correctly. You can't compare them like that. You would have to write it like this:

if letter == "a" or letter == "e" or letter == "i" or letter == "o" or letter == "u":

To shorten this, just write:

if letter in "aeiou":

Here, you check whether the letter is in the string "aeiou".

In your second example you also reset value to zero everytime a vowel is found. This will lead to value being only either 1, or not defined. Put value = 0 before the for-loop and it should work.