Strings & Characters

Access by index: str[i]

Clone strings: str*2

Length of strings: len(str)

Useful Methods#

Method Name	Use	Explanation
`center`	`astring.center(w)`	Returns a string centered in a field of size `w`
`count`	`astring.count(item)`	Returns the number of occurrences of `item` in the string
`ljust`	`astring.ljust(w)`	Returns a string left-justified in a field of size `w`
`lower`	`astring.lower()`	Returns a string in all lowercase
`rjust`	`astring.rjust(w)`	Returns a string right-justified in a field of size `w`
`find`	`astring.find(item)`	Returns the index of the first occurrence of `item`
`split`	`astring.split(schar)`	Splits a string into substrings at `schar`
`index`	`astring.index(str, beg=0, end=len(astring))`	Same as `find()`, but raises exception if sub is not found
`rindex`	`astring.rindex(str, beg=0 end=len(astring))`	Returns last index where the substring `str` is found, or raises an exception if no such index exists
`lower`	`astring.lower()`	Converts string to uppercase
`upper`	`astring.upper()`	Converts string to lowercase

Note: As compared to lists, strings cannot be modified - strings are immutable.

Sorting a String#

sorted(str_s) does the job of converting a string into an array of its sorted characters. Returns the array.

Reversing String#

text = "hello"
text_reversed = text[::-1]

Replacing Characters in a String#

We can use the replace function to replace characters:

replace() is an inbuilt function in Python programming language that returns a copy of the string where all occurrences of a substring is replaced with another substring.

# old – old substring you want to replace.
# new – new substring which would replace the old substring.
# count – the number of times you want to replace the old
# substring with the new substring. (Optional )
string.replace(old, new, count)

Character Case Operations#

isupper(), islower(), lower(), upper()

Check if Alphanumeric#

To check if a character is alphanumeric, use ch.isalnum().