Find position of a character in given string Python (original) (raw)
Last Updated : 30 Apr, 2025
Given a string and a character, our task is to find the first position of the occurrence of the character in the string using Python. For example, consider a string **s = “Geeks” and character **k = ‘e’, in the string s, the first occurrence of the character ‘e’ is at **index1. Let’s look at various methods of solving this problem:
Using Regular Expressions (re.search())
**Regex (Regular Expressions) are patterns used to match sequences in text. With re.search(), we can find the first match of a pattern and get its position.
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Python
``
`import re
s = 'Geeksforgeeks' k = 'for'
match = re.search(k, s) print("starting index", match.start()) print("start and end index", match.span())
`
``
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Output
starting index 5 start and end index (5, 8)
**Explanation:
- **re.search() returns the first match of the pattern.
- ****.start()** gives the index of the first character.
- ****.span()** gives a tuple (**start, end) of the matched portion.
Using index()
The index() method returns the index of the first occurrence of a character. If not found, it raises a ValueError.
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Python
``
`s = 'xyze' k = 'b'
try: pos = s.index(k) print(pos) except ValueError: print(-1)
`
``
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**Explanation:
- **index() finds the first occurrence and returns its index.
- If the character isn’t found, it raises an error-handled using try-except.
Using a Loop
We can also manually loop through the string to find the first match.
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Python
``
`s = 'GeeksforGeeks' k = 'o'
res = -1 for i in range(len(s)): if s[i] == k: res = i break
print(res)
`
``
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**Explanation:
- Loop checks each character.
- If matched, it returns the index and exits early with break.
Using find()
**find() method returns the index of the first match. If not found, it returns -1.
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Python
``
`s1 = 'abcdef' s2 = 'xyze' k = 'b'
print(s1.find(k))
print(s2.find(k))
`
``
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**Explanation:
- **find() returns index of the first match.
- If no match is found, it returns -1 instead of raising an **error.
Using enumerate() with next()
This approach uses list comprehension and lazy evaluation to get the first index where the character matches.
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Python
``
`def find_pos(s, k): try: return next(i for i, c in enumerate(s) if c == k) except StopIteration: return -1
s = 'xybze' k = 'b' print(find_pos(s, k))
`
``
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**Explanation:
- **enumerate() gives index-character pairs.
- **next() returns the first matching index.
- If not found, **StopIteration is caught and **-1 is returned.
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