Python Data Types and Variables

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Questions and Answers

What will the variable type of 's' be after executing the statement 's = input("Enter temperature: ")'?

Integer

Float

String (correct)

None of the above

Which of the following statements correctly converts a string input to a float?

t = str(input("Enter temperature: "))

t = float(s) (correct)

t = int(s)

t = char(s)

What is the purpose of the 'if t>0:' statement in a code where 't' numerically represents temperature?

To initiate a loop

To check if the temperature is greater than zero (correct)

To prompt for input again

To handle exceptions

Which data type is used for variables that hold decimals in Python?

Float Signup and view all the answers

Which statement is true about variable names in Python?

They are case-sensitive. Signup and view all the answers

What type of error will occur if an arithmetic operation is performed with a string and an integer in Python?

Type Error Signup and view all the answers

What will happen if you try to convert the string '7A' to an integer?

It will raise a run-time error. Signup and view all the answers

What is the correct behavior of the expression 'int(s)' when s = '7.5'?

It will raise a ValueError. Signup and view all the answers

What is specifically noted about how Python and Java handle trailing spaces?

Python ignores trailing spaces, while Java does not. Signup and view all the answers

Regarding the int variable 'j' when s = '7A', which statement is correct?

j assignment will fail due to an error. Signup and view all the answers

What output will the expression + (12, 2.5) produce?

14.5 Signup and view all the answers

What happens if the input format provided to scicalc.py contains excessive spaces?

The program will ignore extra spaces and function correctly. Signup and view all the answers

Which function is used to convert a number to a string in Python?

str() Signup and view all the answers

What will happen if you attempt to convert a non-numeric string to an integer using the int() function?

You will get a run-time error. Signup and view all the answers

Why can’t a float be used as an index in an array?

An index must be a whole number. Signup and view all the answers

Which function would you use to round a number to a specific number of decimal places?

round(x, n) Signup and view all the answers

Which of the following represents a valid conversion from string to float?

'3.14' Signup and view all the answers

What is the output of str(5) + str(3)?

53 Signup and view all the answers

Which data type cannot be created from the bool() function?

Float Signup and view all the answers

Which relational operator would correctly evaluate the comparison of two strings based on lexicographical order, as in ‘ABC’ less than ‘ADC’?

< Signup and view all the answers

In the context of operator precedence, which operator has the lowest precedence level?

Logical AND Signup and view all the answers

To determine a student's pass/fail status based on their course mark, which logical comparison would you use for a ‘Pass’?

mark >= 60 Signup and view all the answers

What is the output of the expression + (5, 3) according to the program's expected behavior?

8.0 Signup and view all the answers

Given that a mark of 80 or above corresponds to a letter grade ‘A’, what range should a student fall under to receive a ‘C’ grade?

60 to 69 Signup and view all the answers

When using conditional statements for grading, how should the indentation level be maintained?

Four spaces should be used for each nested decision Signup and view all the answers

How should inputs be formatted for the program to evaluate them correctly?

Include parentheses and allow spaces Signup and view all the answers

What would the expression - (15, 5) return when processed by the program?

10.0 Signup and view all the answers

What limitation is placed on the programming constructs used in the solution?

No additional library imports permitted Signup and view all the answers

If presented with the input / (20, 4), what should the output be?

5.0 Signup and view all the answers

Which of the following expressions would return a remainder?

% (10, 3) Signup and view all the answers

In the provided context, what does a Boolean expression evaluate to?

A comparison between two numbers Signup and view all the answers

Study Notes

Data Types

int represents natural numbers including negatives (e.g. 0, 1, -1, 2, -2)
float represents real numbers with decimals (e.g. -23.5, -9, 0, 0.5, 1, 2.34)
str represents alphanumeric character strings (e.g. "ITM200", "123ER")

Data Variables

Variable names can be any alphanumeric sequence, but cannot start with a numeral.
Variable names are case-sensitive.
Variable names cannot be Python keywords.
Variables can hold different data types dynamically.
Python is strongly typed, meaning incompatible data type operations will cause runtime errors.

Arithmetic Operators

Operators in Python follow standard order of operations:
- Evaluate expressions within parentheses first.
- Evaluate exponentiation (**).
- Evaluate multiplication, division, modulo, and floor division (*, /, %, //).
- Evaluate addition and subtraction (+, -).

Characters in Python

Python doesn't have a separate character data type.
A character is a string of a single character.
ord() function returns ASCII/Unicode value of a character.
chr() function returns the character for a given ASCII/Unicode value.

Formatting Outputs

str(n) converts n to a string to allow concatenation using +.
round(x, n) rounds x to n digits after the decimal point.

Boolean (Bool) Data Type

Represents True or False values.
Used in logical expressions to evaluate conditions.

Boolean Expressions

Boolean Expressions are used to ask questions which can evaluate to True or False.
Relational operators are used in boolean expressions to compare variables:
- < (less than), > (greater than), >= (greater than or equal to), == (equal to), != (not equal to)
Logical operators work on boolean expressions:
- and, not, or

Rules of Operator Precedence

Parentheses (()) have the highest precedence.
Exponentiation (**) has the second highest.
Multiplication, Division, Modulo, and Floor Division (*, /, %, //) come next.
Addition and Subtraction (+, -) have the lowest precedence.
Logical operators not, and, and or have their own precedence levels.

Simple Decision

The if statement allows conditional code execution.
The else statement provides an alternative code block to be executed when the if condition is not met.

Exercise Notes

Exercise 1, 2, 3, 4, 5, 6 focus on manipulating strings and converting data types.
Homework instructions require a Python program named scicalc.py to evaluate arithmetic expressions.
The program should support various arithmetic operations (+,-,*,/,%) and handle user input.
Program should handle spaces within input expressions and only use basic constructs learned so far.

W3 - Decision

This section introduces decision-making in Python.
Boolean Expressions are key to making these decisions.
if-else and if-elif-else statements provide different paths of code execution depending on conditions.

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Description

This quiz tests your knowledge of Python data types, variable naming rules, and arithmetic operators. Understand how integers, floats, and strings work, as well as the importance of Python's strong typing. Prepare to dive into the details of Python's operational hierarchy and character handling.