Variables, Data Types & I/O
Variables, casting, input() and print()
Variables and values
Build a small marks report
Reveal the program in steps, then edit and run the complete version.
student = "Mira"Names, literals, and constants
Variable
A name that refers to a value, such as marks.
Literal
A value written directly in code, such as 91 or "Mira".
Constant
A value intended not to change. Python conventionally uses uppercase names like PASS_MARK; it does not enforce constants.
marks_text = "91" marks = int(marks_text) average = float(marks) message = str(average) print(type(marks_text), marks_text) print(type(marks), marks) print(type(average), average) print(type(message), message)
Output
Your program's output will appear here.
Common Python mistakes
NameError: name 'mark' is not defined
NameError: A name was used before Python could find a variable or function with that name.
IndexError: list index out of range
IndexError: The requested position is outside the items in this list or sequence.
KeyError: 'email'
KeyError: That key does not exist in this dictionary.
TypeError: can only concatenate str (not "int") to str
TypeError: This operation does not work with the kind of value it received.
ZeroDivisionError: division by zero
ZeroDivisionError: A number cannot be divided by zero.
SyntaxError: invalid syntax
SyntaxError: Python could not understand the structure of this line. Check spelling, brackets, colons, and quotes.
IndentationError: expected an indented block
IndentationError: The spaces at the start of a line do not match Python's block structure.
Meet Python’s core data types
Choose a type to see a visual example and run a small operation.
Whole, decimal, and complex numeric values.
roll_number = 82 average = 91.5 print(type(roll_number)) print(type(average)) print(roll_number + 3)
Output
Your program's output will appear here.
Common Python mistakes
NameError: name 'mark' is not defined
NameError: A name was used before Python could find a variable or function with that name.
IndexError: list index out of range
IndexError: The requested position is outside the items in this list or sequence.
KeyError: 'email'
KeyError: That key does not exist in this dictionary.
TypeError: can only concatenate str (not "int") to str
TypeError: This operation does not work with the kind of value it received.
ZeroDivisionError: division by zero
ZeroDivisionError: A number cannot be divided by zero.
SyntaxError: invalid syntax
SyntaxError: Python could not understand the structure of this line. Check spelling, brackets, colons, and quotes.
IndentationError: expected an indented block
IndentationError: The spaces at the start of a line do not match Python's block structure.
Input and output
Ask a question, then use the answer
When you run this example, enter a name in the prompt. Python’s input() returns text, so use int() when you need a number.
name = input("What is your name? ")
print("Welcome,", name)
year = int(input("What semester are you in? "))
print("Semester", year, "— keep practising!")Output
Your program's output will appear here.
Common Python mistakes
NameError: name 'mark' is not defined
NameError: A name was used before Python could find a variable or function with that name.
IndexError: list index out of range
IndexError: The requested position is outside the items in this list or sequence.
KeyError: 'email'
KeyError: That key does not exist in this dictionary.
TypeError: can only concatenate str (not "int") to str
TypeError: This operation does not work with the kind of value it received.
ZeroDivisionError: division by zero
ZeroDivisionError: A number cannot be divided by zero.
SyntaxError: invalid syntax
SyntaxError: Python could not understand the structure of this line. Check spelling, brackets, colons, and quotes.
IndentationError: expected an indented block
IndentationError: The spaces at the start of a line do not match Python's block structure.