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)
But we can combine strings and numbers by using f-strings or the format() method!
To concatenate, or combine, two strings you can use the + operator.
Merge variable a with variable b into variable c:
a = "Hello"
b = "World"
c = a + b
print(c)
Python has a set of built-in methods that you can use on strings.
The upper() method returns the string in upper case:
a = "Hello, World!"
print(a.upper())
The lower() method returns the string in lower case:
a = "Hello, World!"
print(a.lower())
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])
Note: The first character has index 0.
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")
print('Hello')
You can use quotes inside a string, as long as they don’t match the quotes surrounding the string: Continue reading Python Strings
There may be times when you want to specify a type on to a variable. This can be done with casting. Python is an object-orientated language, and as such it uses classes to define data types, including its primitive types.
Casting in python is therefore done using constructor functions:
There are three numeric types in Python:
intfloatcomplexVariables of numeric types are created when you assign a value to them:
x = 1 # int y = 2.8 # float z = 1j # complex
To verify the type of any object in Python, use the type() function : Continue reading Python Numbers
In programming, data type is an important concept.
Variables can store data of different types, and different types can do different things.
Python has the following data types built-in by default, in these categories:
| Text Type: | str |
| Numeric Types: | int, float, complex |
| Sequence Types: | list, tuple, range |
| Mapping Type: | dict |
| Set Types: | set, frozenset |
| Boolean Type: | bool |
| Binary Types: | bytes, bytearray, memoryview |
| None Type: | NoneType |
You can get the data type of any object by using the type() function:
Print the data type of the variable x:
x = 5
print(type(x))
Variables that are created outside of a function (as in all of the examples in the previous pages) are known as global variables.
Global variables can be used by everyone, both inside of functions and outside.
Create a variable outside of a function, and use it inside the function
x = "awesome"
def myfunc():
print("Python is " + x)
myfunc()
If you create a variable with the same name inside a function, this variable will be local, and can only be used inside the function. The global variable with the same name will remain as it was, global and with the original value. Continue reading Python – Global Variables
The Python print() function is often used to output variables.
x = "Python is awesome"
print(x)
In the print() function, you output multiple variables, separated by a comma:
x = "Python"
y = "is"
z = "awesome"
print(x, y, z)
You can also use the + operator to output multiple variables: Continue reading Python – Output Variables