str.find()

str.find(sub[, start[, end]])

The .find() method searches for a substring within a string and returns the lowest index where the substring is found. Unlike .index(), it returns -1 when the substring does not exist instead of raising a ValueError.

Syntax

str.find(sub[, start[, end]])

Parameters

Parameter	Type	Default	Description
sub	str	—	The substring to search for
start	int	0	Beginning index to search from
end	int	len(str)	Ending index to search up to

Return Value

Returns an integer representing the lowest index where the substring is found. Returns -1 if the substring is not present in the string.

Examples

Basic search

text = "Hello, world"
print(text.find("world"))
# 7

print(text.find("Python"))
# -1

Using start parameter

text = "Hello, hello, hello"
print(text.find("hello"))
# 0

print(text.find("hello", 1))
# 7

Using start and end

text = "Hello, world"
print(text.find("l", 0, 5))
# 2

print(text.find("l", 0, 3))
# 2

Practical use case

def highlight_word(text, word):
    idx = text.find(word)
    if idx != -1:
        return text[:idx] + "[" + word + "]" + text[idx + len(word):]
    return text

print(highlight_word("Find the word in this sentence", "word"))
# Find the [word] in this sentence

Common Patterns

Check before using

text = "Python is great"
if text.find("is") != -1:
    print("Found!")

Find all occurrences

text = "apple banana apple apple"
start = 0
while True:
    idx = text.find("apple", start)
    if idx == -1:
        break
    print(f"Found at {idx}")
    start = idx + 1

See Also

• str.rfind()
• str.count()
• str.startswith()