Python String Methods - Set 1 (find, rfind, startwith, endwith, islower, isupper, lower, upper, swapcase & title)

Some of the string basics have been covered in the below articles:

Strings Part-1
Strings Part-2

The important string methods will be discussed in this article

1. find("string", beg, end) :- This function is used to find the position of the substring within a string. It takes three arguments:

• substring: The string to search for.
• beg (starting index, default = 0).
• end (ending index, default = string length).

returns -1 if the substring is not found in the given range.
returns the first occurrence of the substring if found.

2. rfind("string", beg, end) :- This function has the similar working as find(), but it returns the position of the last occurrence of string.

Output: 

The first occurrence of str2 is at : 8
The last occurrence of str2 is at : 21

Time complexity : O(n) 
Auxiliary Space : O(1)

3. startswith("string", beg, end) :- The purpose of this function is to return true if the function begins with mentioned string(prefix) else return false.
4. endswith("string", beg, end) :- The purpose of this function is to return true if the function ends with mentioned string(suffix) else return false.

Output: 

str1 begins with : geeks
str1 does not end with : geeks

Time complexity : O(n) 
Auxiliary Space : O(1)

5. islower("string") :- This function returns true if all the letters in the string are lower cased, otherwise false.
6. isupper("string") :- This function returns true if all the letters in the string are upper cased, otherwise false.

Output: 

All characters in str are not upper cased
All characters in str1 are lower cased

Time complexity : O(n) 
Auxiliary Space : O(1)

7. lower() :- This function returns the new string with all the letters converted into its lower case.
8. upper() :- This function returns the new string with all the letters converted into its upper case.
9. swapcase() :- This function is used to swap the cases of string i.e upper case is converted to lower case and vice versa.
10. title():- This function converts the string to its title case i.e the first letter of every word of string is upper cased and else all are lower cased.

Output: 

 The lower case converted string is : geeksforgeeks is for geeks
 The upper case converted string is : GEEKSFORGEEKS IS FOR GEEKS
 The swap case converted string is : gEEKSfORgEEKS IS FoR gEEkS
 The title case converted string is : Geeksforgeeks Is For Geeks

Time complexity : O(n) 
Auxiliary Space : O(1)