Python String count() Method

Python String count() function is an inbuilt function in python programming language that returns the number of occurrences of a substring in the given string.

Syntax:

string.count(substring, start=…, end=…)

Parameters: 

• The count() function has one compulsory and two optional parameters. 
  • Mandatory parameter: 
    • substring – string whose count is to be found.
  • Optional Parameters:
    • start (Optional) – starting index within the string where the search starts. 
    • end (Optional) – ending index within the string where the search ends.

Return Value:

count() method returns an integer that denotes number of times a substring occurs in a given string. 

Example 1: Implementation of the count() method without optional parameters

Python3

# Python program to demonstrate the use of
# count() method without optional parameters

# string in which occurrence will be checked
string = "geeks for geeks"

# counts the number of times substring occurs in
# the given string and returns an integer
print(string.count("geeks"))

Output:

2

Time Complexity: O(n), where n is the length of the string. This is because we need to traverse the entire string to count the occurrence of the substring.
Auxiliary Space: O(1), as we are not using any extra space in the program, only a string variable is used to store the input string.

Example 2: Implementation of the count() method using optional parameters

Python3

# Python program to demonstrate the use of
# count() method  using optional parameters

# string in which occurrence will be checked
string = "geeks for geeks"

# counts the number of times substring occurs in
# the given string between index 0 and 5 and returns
# an integer
print(string.count("geeks", 0, 5))

print(string.count("geeks", 0, 15))

Output:

1
2

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