How to Get Character Position (Index) in a String in Python(Examples)

How to Get Character Position (Index) in a String in Python(Examples)

This tutorial explains how to determine the position of a character in a given string in the Python language.

A string is a sequence of characters enclosed in double quotes, and the characters in a string are indexed starting from 0.

For example, the starting character position is 0.

How to Get Character Position in a String in Python?

  • Using the find() Function

The find() function checks the given substring’s position and returns the position if a matching substring is found. It returns -1 if no match is found.

Syntax:

str.find(substring[, start[, end]])¶

Arguments:

substring: Substring to search in the given string; returns the first occurrence of the string. start and end options are optional indices. For example, start=1 and end=4 consider characters from position 1 to position 3.

Returns:

  • Index position if found.
  • -1 is returned if no matching character/substring is found in the given string.

This function is case-sensitive.

Here is an example

name="John"

print( name.find('o'))
print( name.find('J'))
print( name.find('j'))

Output:

1
0
-1
  • Using index() function The index() function returns the position or index of a given character in a string.

Syntax:

string.index(charcter[, start[, end]])

Arguments:

character: Character to search in the given string; returns the first occurrence of the character. start and end options are optional indices. For example, start=1 and end=4 consider characters from position 1 to position 3.

Returns:

  • Index position if found.
  • Throws a ValueError if no matching character is found in the given string.

This function is case-sensitive.

Here is an example

name="John"

print( name.index('o'))
print( name.index('J'))
print( name.index('j'))
1
0
Traceback (most recent call last):
File "a:\work\python\string.py", line 5, in <module>
print( name.index('j'))
ValueError: substring not found

Using a For Loop with the enumerated Function

This method involves finding a position using brute force search:

  • Iterate through the string using the enumerate function.
  • Use a for loop with an index syntax to check each character and return the index if a matching character is found.

Here is an example

name="John"

for index, character in enumerate(name):
if "J"==character: {
print(index)
}
0

Conclusion

In this tutorial, you learned multiple ways to find the position of a character in a string:

  • index() function
  • find() function
  • For loop with index syntax

The index() function is recommended as it handles both matching and non-matching cases, returning the position of the character and performing well in terms of performance compared to the other two approaches.

The disadvantages of the other approaches are:

find() method throws a ValueError if no match is found. For loop iterates over all characters in a string in the worst case, making it less advisable in terms of performance.

Learned multiple ways to find the position of a character in a string

  • index() function
  • find() function
  • for loop with index syntax

The first approach is better, It checks for matching and nonmatching use cases and returns the position of a number, and good in performance compared with the other two approaches the disadvantages with the other are

  • find() method throws ValueError if no match is found.
  • For loop iterates all characters in a string in the worst case, so not advisable in terms of performance.