String in Python is an inbuilt object that is represented using
str
keyword. Like other objects string support some built methods and find() is one of those. The Python string
find(sub)
method or function accepts a substring value and return its first occurring index value in the given string. If the substring value is not present in the given string, the Python string
find()
function return -1 value.
Note: In Python, everything is an object, including Python data types. The inbuilt functions associated with data type or structures are known as methods. You can also interchangeably use the term functions and methods. But it is suggested to call the object’s functions as methods .
Python String find() Method Syntax and Parameter
string.find(substring, start, end)
The string find() method can accept three parameters
- substring
- start
- end
Substring:
It is a string value which index we want to find out from the given string.
start
(optional):
It is an optional parameter and by default, its value is 0. It is an integer number that represent the starting index value of a given string from where the searching of substring should begin.
end
(optional):
It is also an optional parameter and by default, its value is equal to the length of the given string. It is an integer value that represents the end index value for the given string up to which the searching for substring should limit. The Python String find() method only return the lowest index value of the given string where it found the sub string. If the given string has multiple substrings, the method will only return the first occurrence.
How to Use Python String find() method Example
With the help of string
find()
method we can point out the substring starting index value within a given string. The string
find()
method come very useful during string analysis and manipulation.
Python string find() Examples
Example 1
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "Tech"
>>> print("The substring", sub, "is at", string.find(sub))
The substring Tech is at 6
In the above example, you can see that the starting index value of
Tech
in
string
is
6
, that’s why the find method returns
6
as an output.
Example 2
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "python"
>>> print("The substring", sub, "is at", string.find(sub))
The substring python is at -1
As
sub
python
is not present in the
string,
the
find()
method return
-1
.
Example 3
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "tech"
>>> print("The substring", sub, "is at", string.find(sub))
The substring tech is at -1
The
find()
method matches the
substring
each character with the
string
and return the exact index position for the first occurrence. The
find()
method is case sensitive, the case of substring should also match the case of given string else the
find()
method return -1 as no result found.
Example 4
Python string find(start) method with start parameter
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "Tech"
>>> print("The substring", sub, "is at", string.find(sub,7))
The substring Tech is at 27
In this example the
find(sub, 7)
,
method starts searching the
Tech
substring from the 7
th
index value of the
string.
That’s why it ignores all the first 6 characters of the
string
.
Example 5
Python string
find(start,end)
method with start and end parameters
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "Geek"
>>> print("The substring", sub, "is at", string.find(sub,0, 14))
The substring Geek is at -1
In this example the
find(sub, 0,14)
,
method starts searching the
Geek
substring from the
0
th
index value up to
14
of the
string.
Although the first occurrence of
Geek
start at
11
but it ends at
15,
and we have specified the
end
parameter to
14
so the
find()
method is not able to find
Geek
and return
-1
.
Python String rfind() method
The Python string
rfind()
function is similar to the Python string
find()
function, the only difference is the
find()
return the first occurrence index value and
rfind()
return the last occurrence index value of substring. Apart from this difference both
find()
and
rfind()
methods are pretty same. Both return -1 if the substring is not present in the given string.
Python rfind() syntax
string.rfind(substring, start, end)
Python rfind() method Example:
Example 1
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "Geek"
>>> print("The last substring", sub, "is at", string.rfind(sub))
The last substring Geek is at 31
The last occurrence of
Geek
start from
31
st
index position in
TechGeekBuzz.com
.
That’s why
rfind()
method return
31
,
instead of
11
which is the first
Geek
substring position.
Example 2
>>> string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
>>> sub = "geek"
>>> print("The last substring", sub, "is at", string.rfind(sub))
The last substring geek is at -1
Similar to the
find()
method
rfind()
return -1 if it does not find the substring in the given string.
Python string index() method
The Python string
index()
method also returns the index value of the first occurrence of the substring. But unlike
find()
method the
index()
method throws an exception or error if the sub string is not present in the given string.
Python string index() method syntax
string.index(substring, start,end)
Python string index() method Examples
Example 1
string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
sub = "Tech"
print("The first occurrence of", sub, "is at", string.index(sub))
print("The first occurrence of", sub, "is at", string.find(sub))
Output
The first occurrence of Tech is at 6
The first occurrence of Tech is at 6
Example 2
string = "Hello Tech Geek WelCome to TechGeekBuzz.com"
sub = "tech"
print("The first occurance of", sub, "is at", string.index(sub))
Output
print("The first occurance of", sub, "is at", string.index(sub))
ValueError: substring not found
Conclusion
The Python string
find()
method returns the first occurrence index value of the substring. It can accept three parameters
substring, start
and
end.
Similar to the find() method, Python string also supports
rfind()
method which returns the last occurrence index value of the substring in a given string.
The Python string
index()
method also returns the first occurrence index value of substring, but if the substring is not present in the given string the
index()
method throws the ValueError.
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