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Python – Check If String Starts with a Letter

In this tutorial, we will look at how to check if a string in Python starts with a letter (alphabet) or not with the help of some examples.

How to check if a string starts with an alphabet character?

python check if string starts with a letter

To check if a string in Python starts with a letter or not, check if the first character in the string is an alphabet or not using the string isalpha() function.

The built-in string isalpha() function in Python takes a string and returns True if all the characters in the string are alphabet and there is at least one character in the string. It returns False otherwise.

So, use the string isalpha() function to check if the first character in the string (character at index 0) is an alphabet or not. The following is the syntax –

# check if string starts with an alphabet
s[0].isalpha()

It returns True if the string starts with an alphabet.

Examples

Let’s now look at some examples. First, we will create some strings that we will use throughout this tutorial.

# create strings
s1 = "apple"
s2 = "7eleven"
s3 = "$500"
s4 = ""

# display the strings
print(s1)
print(s2)
print(s3)
print(s4)

Output:

apple
7eleven
$500

Here, we created four strings – s1, s2, s3 and s4. The string s1 starts with a letter, the string s2 starts with a number, the string s3 starts with the special character '$' and the string s4 is an empty string.

Let’s now check if the strings s1, s2, and s3 start with an alphabet or not.

# check if string starts wtih a letter
print(s1[0].isalpha())
print(s2[0].isalpha())
print(s3[0].isalpha())

Output:

True
False
False

We get True for s1 as it does start with an alphabet. We get False for s2 and s3 as they do not start with an alphabet.

Now let’s apply the above method to the empty string, s4.

# check if string starts wtih a letter
print(s4[0].isalpha())

Output:

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
Input In [4], in <module>
      1 # check if string starts wtih a letter
----> 2 print(s4[0].isalpha())

IndexError: string index out of range

We get an IndexError because we’re trying to access an index that does not exist (an empty string does not have a 0 index).

To avoid the above error, you can first check whether the string is non-empty and then proceed to check if the first character is an alphabet or not. See the example below –

# function to check if string starts wtih a letter
def check_str_starts_with_alpha(s):
    if s and s[0].isalpha():
        return True
    else:
        return False

# check if string starts wtih a letter
print(check_str_starts_with_alpha(s4))

Output:

False

We get False as the output for the empty string.

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Author

  • Piyush

    Piyush is a data scientist passionate about using data to understand things better and make informed decisions. In the past, he's worked as a Data Scientist for ZS and holds an engineering degree from IIT Roorkee. His hobbies include watching cricket, reading, and working on side projects.