Value
A value is a single piece of data. It can be used as a literal or stored in a variable.
Examples:
- 45
- ”Liam”
- True
- 64.52
- [“apple”, “kiwi”, “pear”]
Variables can only contain values. So if it is contained within a variable - it is a value.
Expression
An expression is an operation of values and/or variables that will result in a value.
Typically, you get a different value output than the input - as you are performing a mathematical operation usually (and most of the time you won’t be doing a * 1 operation).
Examples:
- 32 * 4
- 15 - 2
- 43 / 7
- 3 == 5
- ”hello” + “world”
- 4 > 2
- ”hello” * 4
- input(“What is your name? ”) * 6
- ((12 * 6) /4 ) + 8
Expressions are used to modify or compare values. They may contain a function call (ie, int(3.4) * 5 is still an expression).
Data Types do matter in expressions - so whilst you can multiply a string by an integer, you cannot divide a string by an integer.
So Bob * 4 is valid and results in “BobBobBobBob”
But Bob / 2 is not valid and will return an error.
A division operation will always return a float - even if the inputs were integers.
Statement
A statement is any valid fragment of code. (A command, any line of code etc).
Examples:
- print(“Hello world”)
- import random
- 25 == 30
- if int(age) == 30:
Multiple types
Something can be or contain multiple types. So a statement may contain an expression which may then contain a value.