What are Strings?
Strings are an ordered collection or sequence of characters. They are used to store information in the form of text. Strings are immutable in Python. Once a String is assigned a value, its value cannot be modified (It can be reassigned or completely deleted).
How to create strings in Python?
Strings are created using quotations in Python. Single, Double or Triple quotes can be used to denote a string in Python code. A simple python string can be created
my_var = 'hello' #String Literal using single quotes #or my_var = "hello" #String Literal using double quotes
The key difference between declaring a string literal using single or double quotes is that with single quotes, the usage of the double quotes is allowed inside the single quotes.
For example, with single quotes, you can write something
my_var = 'Elon Musk just tweeted that "Been spending most of our lives living in the past time paradise!""' print(my_var)
If you use double quotes instead,
my_var = "Elon Musk just tweeted that "Been spending most of our lives living in the past time paradise!"" print(my_var)
If we want to use both the single and double quotes in a string, we make use of the triple quotes.
my_var = ''' 'Elon Musk just tweeted that "Been spending most of our lives living in the past time paradise." ''' print(my_var)
As you can see in the above example, we can also use triple quotes to write multiline string literals.
If you want to write multiline strings in the code but only want the output to be in a single line, you can use "\" at the end of each line.
my_var = '''\ 'Elon Musk just tweeted that \ "Been spending most of our lives living in the past time paradise"'\ ''' print(my_var)
"\" also works with single quotes and double quotes.
Accessing strings in Python
We can access an element in a string by using the index of that element. We put the index inside the  parentheses.
sampleString = "Hello This is Joey from Arizona" print(sampleString) #accessing 7th index element print(sampleString) #accessing 12th index element print(sampleString[-3]) #accessing 3rd index element from the end print(sampleString[-10]) #accessing 10th index element from the end print(sampleString[:10]) #accessing first 10 elements using slicing print(sampleString[6:]) #accessing all the elements after starting from the 6th index print(sampleString[-5:]) #accessing all the elements starting from 5th index element from the end print(sampleString[1::2]) #accessing all the elements starting from the 1st index with increment of 2
As you can see in the above code snippet, we can also use negative indices to access elements by referring to them with respect to the end of the string. Similarly, slicing also works with strings just like any other sequence in Python.
As mentioned above already, Python strings are immutable. You can not append a String or delete a particular element from a String. Instead, you can delete the whole String using the del keyword or reassign it with a different value.
sampleString = "Hello This is Joey from Arizona" del sampleString print(sampleString)
Operations on Strings
Concatenation of Strings
Multiple strings can be combined to create a new string as a result. We can do concatenation in Python using the + operator.
sampleString1 = "Hello " sampleString2 = "This is Joey " sampleString3 = "from Arizona" sampleString4 = sampleString1 + sampleString2 + sampleString3 print(sampleString4) print("A" + "B" + "C")
Repeating a string multiple times
The * operator is used to multiply a string with a integer value to repeat it a specified number of times.
sampleString1 = "Hello " sampleString2 = sampleString1*3 print(sampleString4)
Iterating over a string
Since String is a sequence type in Python, we can use loops to iterate through its elements.
sampleString1 = "Hello " for character in sampleString1: print(character)
Escape sequences allow the programmer to use special characters in a string. For example, if you want to use single quotes inside a string that is denoted with single quotes, you need the escape sequences to represent the inner single quotes. An escape sequence is denoted using the backslash "\"inside the string.
sampleString1 = '\'This is Joey\'' print(sampleString1)
Other available escape sequences in Python:
|\r||ASCII Carriage Return|
|\t||ASCII Tab (Horizontal)|
|\v||ASCII Tab (Vertical)|
Methods available methods for strings in Python are :
|capitalize||Return the string with all characters capitalized|
|casefold||Return a string for caseless comaprision|
|center||Return a centered string|
|count||Return the number of occurrences of an element|
|encode||Encode the string with a specified encoding|
|endswith||Return True if the string ends with a given suffix Else return false|
|find||Return the first index of a given substring inside a string Return -1 on failure|
|format||Return a substituted version of the string using substitutions from argos and kwargs|
|index||Return the first index of a given substring inside a string Raises error on failure|
|isalnum||Return True if the string is alpha-numeric Else return False|