How to Use startswith in Python: Syntax and Examples

In Python, use the startswith() method on a string to check if it begins with a specified prefix. It returns True if the string starts with that prefix, otherwise False. You can also check multiple prefixes by passing a tuple of strings.

Syntax

The startswith() method checks if a string starts with the given prefix.

• string.startswith(prefix): Returns True if string starts with prefix.
• prefix can be a string or a tuple of strings.
• Optional start and end parameters specify the substring range to check.

python

string.startswith(prefix, start=0, end=len(string))

Example

This example shows how to use startswith() to check if a string begins with a certain prefix or any of multiple prefixes.

python

text = "Hello, world!"

# Check if text starts with 'Hello'
print(text.startswith("Hello"))  # True

# Check if text starts with 'Hi'
print(text.startswith("Hi"))     # False

# Check if text starts with either 'Hi' or 'Hello'
print(text.startswith(("Hi", "Hello")))  # True

# Check starting from index 7
print(text.startswith("world", 7))  # True

Output

True
False
True
True

Common Pitfalls

Common mistakes when using startswith() include:

• Passing a list instead of a tuple for multiple prefixes (only tuples work).
• Forgetting that startswith() is case-sensitive.
• Not using the optional start and end parameters correctly.

Example of wrong and right usage:

python

# Wrong: using list instead of tuple
text = "Python"
print(text.startswith(["Py", "Ja"]))  # Raises TypeError

# Right: use tuple
print(text.startswith(("Py", "Ja")))  # True

# Case sensitivity
print(text.startswith("py"))  # False because 'p' != 'P'

Output

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
TypeError: startswith first arg must be str or a tuple of str, not list
True
False

Quick Reference

Usage	Description
string.startswith(prefix)	Returns True if string starts with prefix.
string.startswith((p1, p2))	Returns True if string starts with any prefix in tuple.
string.startswith(prefix, start)	Checks from index start to end of string.
string.startswith(prefix, start, end)	Checks substring from start to end indexes.

Key Takeaways

Use startswith() to check if a string begins with a specific prefix.

Pass a tuple to check multiple prefixes at once, not a list.

startswith() is case-sensitive; 'Hello' and 'hello' differ.

Optional start and end let you check parts of the string.

It returns a boolean: True if the prefix matches, otherwise False.