We'll start by talking about variables. In programming, a variable is a named location used to
store data in memory. It is called a variable because its value can vary throughout the
execution of a program. Variables must be given unique names, called identifiers. In Python,
variable names are case sensitive and cannot start with a number. They can contain letters,
numbers, and underscores.
For example, let's say we want to store the number of apples I have in a variable named
apples. We can do this with the following code:
apples = 5
Now, apples is a variable that stores the value 5. We can use this variable in calculations,
such as adding more apples:
apples = apples + 3
print(apples)
This will output 8, because we added 3 to the value stored in the apples variable.
Next, let's talk about data types. A data type is an attribute that tells what kind of data a
particular variable can hold. There are several basic data types in Python, including int, float,
str, and bool.
int is short for integer, which is a whole number, positive or negative, without decimals. For
example:
num_apples = 10
num_oranges = -5
float is short for floating point number, which is a number with decimals. For example:
price_per_apple = 0.5
price_per_orange = 0.35
str is short for string, which is a sequence of characters surrounded by quotes. Strings can
be enclosed in either single quotes or double quotes. For example:
name = "Alice"
greeting = 'Hello, world!'
bool is short for boolean, which is a logical value that can be either True or False. For
example:
is_hungry = True
is_tired = False
We can also use data types to perform type conversions, such as converting a string to an
integer:
age_str = "25"
age_int = int(age_str)
print(type(age_int))
This will output <class 'int'>, because we converted the string "25" to an integer using the
int() function.
store data in memory. It is called a variable because its value can vary throughout the
execution of a program. Variables must be given unique names, called identifiers. In Python,
variable names are case sensitive and cannot start with a number. They can contain letters,
numbers, and underscores.
For example, let's say we want to store the number of apples I have in a variable named
apples. We can do this with the following code:
apples = 5
Now, apples is a variable that stores the value 5. We can use this variable in calculations,
such as adding more apples:
apples = apples + 3
print(apples)
This will output 8, because we added 3 to the value stored in the apples variable.
Next, let's talk about data types. A data type is an attribute that tells what kind of data a
particular variable can hold. There are several basic data types in Python, including int, float,
str, and bool.
int is short for integer, which is a whole number, positive or negative, without decimals. For
example:
num_apples = 10
num_oranges = -5
float is short for floating point number, which is a number with decimals. For example:
price_per_apple = 0.5
price_per_orange = 0.35
str is short for string, which is a sequence of characters surrounded by quotes. Strings can
be enclosed in either single quotes or double quotes. For example:
name = "Alice"
greeting = 'Hello, world!'
bool is short for boolean, which is a logical value that can be either True or False. For
example:
is_hungry = True
is_tired = False
We can also use data types to perform type conversions, such as converting a string to an
integer:
age_str = "25"
age_int = int(age_str)
print(type(age_int))
This will output <class 'int'>, because we converted the string "25" to an integer using the
int() function.
