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Python basics: data types, input and output
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Every program takes input, processes it and gives output. Choosing the right data type makes the processing work.
Data types
Input and output
input() shows a prompt and always returns a string.
To do maths with it, convert it: int() for whole numbers, float() for decimals. str() turns a number into a string.
print() displays output. Separate items with commas.
name = input("Name: ")
age = int(input("Age: "))
print("Hello", name)
print("Next year you will be", age + 1)
To do maths with it, convert it: int() for whole numbers, float() for decimals. str() turns a number into a string.
print() displays output. Separate items with commas.
name = input("Name: ")
age = int(input("Age: "))
print("Hello", name)
print("Next year you will be", age + 1)
Assignment and initialisation
Assignment stores a value in a variable: score = 0.
Initialisation is the first assignment, giving a variable its starting value before it is used.
Python reads from right to left: in total = total + 5, it works out total + 5 first, then stores it.
Initialisation is the first assignment, giving a variable its starting value before it is used.
Python reads from right to left: in total = total + 5, it works out total + 5 first, then stores it.
The user types Sam and 14 for the program above. What is output?
- name = "Sam", age = int("14") = 14
- print("Hello", name) gives Hello Sam
- age + 1 = 15
Answer: Hello Sam / Next year you will be 15
Integer, real, Boolean, character and string are the basic types. input() returns a string, so use int() or float() before doing maths. Initialise variables before using them.
The interactive lesson includes the diagrams for this topic.
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