Strings
Strings in python are surrounded by either single quotation marks, or double quotation marks.
'hello' is the same as "hello".
You can display a string literal with the print() function:
print('Hello')
Assign String to a Variable
Assigning a string to a variable is done with the variable name followed by an equal sign and the string:
a = "Hello"
print(a)
Multiline Strings
You can assign a multiline string to a variable by using three quotes:
a = """Lorem ipsum dolor sit amet,
consectetur adipiscing elit,
sed do eiusmod tempor incididunt
ut labore et dolore magna aliqua."""
print(a)
Slicing
You can return a range of characters by using the slice syntax.
Specify the start index and the end index, separated by a colon, to return a part of the string.
Get the characters from position 2 to position 5 (not included):
b = "Hello, World!"
print(b[2:5])
Slice From the Start
By leaving out the start index, the range will start at the first character:
b = "Hello, World!"
print(b[:5])
Slice To the End
By leaving out the end index, the range will go to the end:
b = "Hello, World!"
print(b[2:])
Negative Indexing
Use negative indexes to start the slice from the end of the string:
Example
Get the characters:
From: "o" in "World!" (position -5)
To, but not included: "d" in "World!" (position -2):
b = "Hello, World!"
print(b[-5:-2])
Python - Modify Strings
Upper Case
The upper() method returns the string in upper case:
a = "Hello, World!"
print(a.upper())
Lower Case
The lower() method returns the string in lower case:
a = "Hello, World!"
print(a.lower())
Remove White space
The strip() method removes any white space from the beginning or the end:
a = " Hello, World! "
print(a.strip()) # returns "Hello, World!"
String Format
As we learned in the Python Variables chapter, we cannot combine strings and numbers like this:
age = 36
txt = "My name is John, I am " + age
print(txt)
Use the format() method to insert numbers
into strings:
age = 36
txt = "My name is John, and I am {}"
print(txt.format(age))
The format() method takes unlimited number of arguments, and are placed into the respective placeholders:
quantity = 3
itemno = 567
price = 49.95
myorder = "I want {}
pieces of item {} for {} dollars."
print(myorder.format(quantity,
itemno, price))
You can use index numbers {0} to be sure the arguments are placed
in the correct placeholders:
quantity = 3
itemno = 567
price = 49.95
myorder = "I want to pay {2}
dollars for {0} pieces of item {1}."
print(myorder.format(quantity,
itemno, price))
