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 3 arguments, substring , starting index( by default 0) and ending index( by default string length).
- It returns “-1 ” if string is not found in given range.
- It returns first occurrence of string 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.
# Python code to demonstrate working of # find() and rfind() str = "geeksforgeeks is for geeks"
str2 = "geeks"
# using find() to find first occurrence of str2 # returns 8 print ( "The first occurrence of str2 is at : " , end = "")
print ( str .find( str2, 4 ) )
# using rfind() to find last occurrence of str2 # returns 21 print ( "The last occurrence of str2 is at : " , end = "")
print ( str .rfind( str2, 4 ) )
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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.
# Python code to demonstrate working of # startswith() and endswith() str = "geeks"
str1 = "geeksforgeeksportal"
# using startswith() to find if str # starts with str1 if str1.startswith( str ):
print ( "str1 begins with : " + str )
else : print ( "str1 does not begin with : " + str )
# using endswith() to find # if str ends with str1 if str1.endswith( str ):
print ( "str1 ends with : " + str )
else :
print ( "str1 does not end with : " + str )
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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.
# Python code to demonstrate working of # isupper() and islower() str = "GeeksforGeeks"
str1 = "geeks"
# checking if all characters in str are upper cased if str .isupper() :
print ( "All characters in str are upper cased" )
else :
print ( "All characters in str are not upper cased" )
# checking if all characters in str1 are lower cased if str1.islower() :
print ( "All characters in str1 are lower cased" )
else :
print ( "All characters in str1 are not lower cased" )
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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.
# Python code to demonstrate working of # upper(), lower(), swapcase() and title() str = "GeeksForGeeks is fOr GeeKs"
# Converting string into its lower case str1 = str .lower();
print ( " The lower case converted string is : " + str1)
# Converting string into its upper case str2 = str .upper();
print ( " The upper case converted string is : " + str2)
# Converting string into its swapped case str3 = str .swapcase();
print ( " The swap case converted string is : " + str3)
# Converting string into its title case str4 = str .title();
print ( " The title case converted string is : " + str4)
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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)