Programming fundamentals: sequence, variables and input/output

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Ghi chú bài học

Sequence

A program is a sequence of instructions executed in order, one after another.
Each instruction is a step that the computer carries out, from top to bottom.
Changing the order of instructions can change the outcome of the program.
The sequence is the simplest program structure; all programs rely on it.
Algorithms are step-by-step procedures that are implemented as sequences of code.

Sequence: each instruction runs in a precise order from start to output.

Variables

A variable is a named storage location in memory that holds a value.
Use the assignment operator (`=`) to store a value in a variable, e.g., `score = 10`.
Variable names should be descriptive, like `age` or `total`, and follow rules (no spaces, start with a letter).
The value of a variable can be changed later by assigning a new value.
Variables allow programs to store and manipulate data dynamically.

A variable is a named storage location whose value can change while the program runs.

Data Types

Common data types include integer (whole numbers), string (text), and boolean (True/False).
Integers are used for counting and arithmetic, e.g., `5`, `-3`.
Strings are sequences of characters enclosed in quotes, e.g., `"Hello"`.
Booleans represent logical values: `True` or `False`.
The type of a variable determines what operations you can perform on it.

Integer, real, string, character and Boolean each store a different kind of value.

Input and Output

Input is data given to the program by the user or another source.
In Python, `input()` reads a line of text from the user and returns it as a string.
Output is information the program produces, often displayed to the user.
In Python, `print()` outputs text or values to the screen.
Input and output allow programs to interact with the outside world.

Every program has the same shape: data enters, instructions transform it, and meaningful output leaves.

Arithmetic Operations

Use arithmetic operators: `+` (addition), `-` (subtraction), `×` (multiplication), `/` (division).
Integer division `//` and modulo `%` give quotient and remainder.
Operations follow standard precedence: multiplication/division before addition/subtraction.
Parentheses `()` can be used to group operations and change order.
Results can be stored in variables or used directly in output.

Arithmetic operators compute values, comparison operators produce a Boolean, and Boolean operators combine them.

String Operations

Strings can be concatenated (joined) using the `+` operator.
Example: `"Hello" + " " + "World"` gives `"Hello World"`.
You can repeat a string with `×`, e.g., `"ha"×3` gives `"hahaha"`.
Use `len()` to find the length of a string.
Strings are immutable; operations create new strings.

Example Program

A simple program: `name = input("What is your name? ")` then `print("Hello, " + name)`.
This shows sequence (two lines), variable storage, input, and output.
Another example: `age = int(input("Age? "))` converts input to integer for arithmetic.
Programs often combine input, processing, and output in sequence.

Debugging and Testing

Testing involves running a program to check it works correctly.
Debugging is finding and fixing errors (bugs) in code.
Common errors: syntax errors (typos), logic errors (wrong results), runtime errors (e.g., division by zero).
Use print statements to trace variable values and locate problems.
Test with different inputs to ensure reliability.

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1.What is a sequence in programming?
Easy
- AA set of instructions executed in order
- BA random order of instructions
- CA type of variable
- DA programming language
2.Which of the following is a correct way to assign the value 10 to a variable called 'score' in Python?
Easy
- Ascore = 10
- B10 = score
- Cscore == 10
- Dvar score = 10
3.What is the output of the following Python code? x = 5 y = 2 print(x + y×3)
Medium
- A11
- B21
- C17
- D13
4.Which data type would be most appropriate to store a person's name?
Easy
- Astring
- Binteger
- Cboolean
- Dfloat
5.What is the purpose of the input() function in Python?
Medium
- ATo read data from the user
- BTo display data to the user
- CTo convert data to a string
- DTo store data in a file
6.What is the value of the variable 'result' after this code runs? num1 = 8 num2 = 3 result = num1 // num2
Medium
- A2
- B2.666...
- C3
- D24
7.Which of the following are valid variable names in Python? (select all that apply)
Medium
- Amy_var
- B2nd_value
- Ctotal
- Duser-name
- Escore1
8.In Python, the print() function is used to display output to the screen.
Easy
True or false?

Thêm câu hỏi

9.In Python, the value of a variable can be changed after it has been assigned.
Easy
True or false?
10.The input() function in Python always returns an integer.
Easy
True or false?
11.Match each Python function or operator to its purpose.
Medium
- print()
- input()
- + (with strings)
- Display output
- Read user input
- Concatenate strings
12.Arrange the following steps in the correct order to create a program that asks for the user's name and prints a greeting.
Medium
- Call input() to get the name
- Print a greeting using the name
- Store the input in a variable
- Start the program
13.What is the output of the following code? name = 'Ada' print('Hello ' + name + '!')
Medium
- AHello Ada!
- BHello name!
- CHello 'Ada'!
- DHello Ada
14.Which of the following correctly converts the string '25' to an integer and adds 5?
Medium
- Aint('25') + 5
- B'25' + 5
- Cint(25) + 5
- Dstr('25') + 5
15.In Python, the expression '5' + '3' results in the integer 8.
Medium
True or false?
16.What is the final value of y after this code? a = 3 b = 2 y = a×b + a - b
Hard
- A7
- B11
- C5
- D9
17.Match each data type to an example value.
Medium
- integer
- string
- boolean
- 42
- Hello
- True
18.Put the following Python statements in the correct order to swap the values of two variables x and y.
Medium
- temp = x
- x = y
- y = temp
19.What will the following code print? num = 10 num = num + 5 num = num×2 print(num)
Hard
- A30
- B25
- C20
- D15
20.Which of the following expressions evaluates to True?
Hard
- A5 > 3
- B5 < 3
- C5 == 3
- D5 ≠ 5
21.In Python, the variable name 'myVariable' is the same as 'myvariable'.
Medium
True or false?
22.Match each operator to its description.
Medium
- +
- -
- ×
- Addition
- Subtraction
- Multiplication
23.Arrange the following steps in the correct order to write and run a Python program that asks for two numbers and prints their sum.
Medium
- Write the code in a text editor
- Run the program
- Use input() to get two numbers
- Convert inputs to integers
- Add the numbers and print the result
24.What is the output of this code? x = 'Hello' y = 'World' print(x + ' ' + y)
Medium
- AHello World
- BHelloWorld
- CHello+World
- DError
25.Which of the following is NOT a valid way to create a variable in Python?
Medium
- Amy_var = 5
- Bmy_var = '5'
- Cmy_var = True
- Dmy var = 5
26.In Python, the input() function can be used to read a number directly without conversion.
Medium
True or false?
27.What is the final value of total after this code? total = 0 for i in range(3): total = total + i
Medium
- A3
- B0
- C6
- D2
28.Which of the following are valid Python data types? (select all that apply)
Medium
- Ainteger
- Bstring
- Cboolean
- Dcharacter
- Ereal
29.In Python, the assignment operator is '='.
Easy
True or false?
30.Match each Python function to its purpose.
Medium
- int()
- str()
- float()
- Convert to integer
- Convert to string
- Convert to float
31.Match each programming term to its correct description.
Easy
- Sequence
- Variable
- Assignment
- Input
- A named storage location for a value
- Statements executed one after another
- The process of giving a value to a variable
- Data provided to a program, often from the user
32.Put the following steps in the correct order to write and run a Python program that asks the user for their age and prints it doubled.
Medium
- Write the code using an editor
- Save the file with a .py extension
- Run the program
- The program asks for input and displays output
33.Which of the following are valid Python variable names? (select all that apply)
Medium
- Ascore1
- B1score
- C_score
- Dscore-1
- Escore total
34.In Python, the order of statements in a program does not affect the output.
Easy
True or false?
35.What is the output of the following Python code? age = input("Enter your age: ") print(age + 5)
Medium
- AIt prints the user's age plus 5
- BIt prints the user's age as a string followed by 5
- CIt causes an error
- DIt prints nothing
36.A program is written to calculate the area of a rectangle. The width is stored in a variable 'w' and the height in 'h'. Which expression correctly calculates the area?
Medium
- Aw×h
- Bw + h
- Cw / h
- Dw - h
37.Consider this Python code: x = 5 y = 2 x = y x = x + 1 What is the final value of x?
Medium
- A3
- B6
- C2
- D5
38.Which of the following Python expressions will result in an integer? (select all that apply)
Medium
- A7 // 2
- B7 / 2
- Cint(7 / 2)
- D7 % 2
- E7 + 2
39.In Python, the statement 'num = num + 1' is an example of updating a variable using its current value.
Easy
True or false?
40.Match each Python operator to its description.
Medium
- //
- %
- **
- +
- Integer division
- Modulo (remainder)
- Exponentiation
- Addition
41.Complete the sentence.
Easy
In programming, a ____ is a named location in memory used to store a value.
42.What is the output of the following code? print(7 % 3)
Medium
43.What is the final value of x after this code runs? x = 4 x = x + 2 x = x×3
Medium
44.What is the term for the process of finding and fixing errors in a program?
Easy
45.Write a single Python statement that assigns the value 100 to a variable named 'total'.
Medium
46.What is the result of the expression 10 / 4 in Python?
Medium
47.Write a Python statement that reads a whole number from the user and stores it in a variable called 'age' as an integer.
Medium
48.What is the result of the expression 2 ** 3 + 1?
Medium
49.What is the name of the process of writing a program in a high-level language and then translating it to machine code?
Easy
50.What is the value of the expression 15 % 4?
Medium
51.Write a Python expression that computes the area of a rectangle with width 5 and height 3.
Medium
52.What is the result of the expression 6 // 2?
Medium
53.Explain why the order of statements in a program is important. Give an example.
Medium
54.Describe the difference between the / and // operators in Python, and give an example of each.
Hard
55.Explain the difference between a variable and a constant. Give an example of each.
Medium
56.What is the output of the following code? print(7 % 3)
Medium
- A0
- B3
- C1
- D2
57.What is the final value of x after this code runs? x = 4 x = x + 2 x = x×3
Medium
- A17
- B20
- C18
- D19
58.What is the result of the expression 10 / 4 in Python?
Medium
- A2.5
- B1.5
- C3.5
- D4.5
59.What is the result of the expression 2 ** 3 + 1?
Medium
- A8
- B11
- C9
- D10
60.What is the value of the expression 15 % 4?
Medium
- A3
- B5
- C2
- D4
61.What is the result of the expression 6 // 2?
Medium
- A5
- B3
- C4
- D2

Ghi chú ôn tập

## Programming Fundamentals: Sequence, Variables, Input/Output ### Sequence - A **program** is a sequence of instructions that a computer follows to perform a task. - Instructions run **in order**, one after another, from top to bottom. - This is called **sequence** – the most basic programming construct. ### Variables - A **variable** is a named storage location in memory that holds a value. - You **assign** a value using `=` (e.g., `score = 10`). - Variables can change value during program execution. - Common **data types**: - **Integer**: whole numbers (e.g., `5`, `-3`) - **String**: text (e.g., `"hello"`) - **Boolean**: `True` or `False` ### Input and Output - **Input** gets data from the user (e.g., `input()` in Python). - **Output** displays data to the user (e.g., `print()` in Python). - Example: `name = input("Enter name: ")` then `print("Hello", name)`. ### Simple Operations - Arithmetic: `+`, `-`, `*`, `/` - String concatenation: joining strings with `+` (e.g., `"a" + "b"` → `"ab"`). - Be careful: input from `input()` is a string; convert with `int()` or `float()` for math. ### Example Program ```python # Ask for age age = input("Enter your age: ") age = int(age) # convert to integer next_age = age + 1 print("Next year you will be", next_age) ``` ### Key Points - Programs are written in **high-level languages** (like Python) that are easier for humans than machine code. - **Debugging** is finding and fixing errors. - **Reliability** means the program gives correct results. --- ## Key Terms - **Sequence**: The order in which instructions are executed. - **Variable**: A named storage location for a value. - **Assignment**: Giving a value to a variable using `=`. - **Data type**: The kind of data a variable holds (integer, string, boolean). - **Input**: Data entered into a program. - **Output**: Data displayed by a program. - **Integer**: A whole number. - **String**: A sequence of characters (text). - **Boolean**: A value that is either True or False. - **Concatenation**: Joining strings together. - **Debugging**: Finding and fixing errors in code. - **High-level language**: A programming language that is easy for humans to read and write. - **Compiler**: A program that translates high-level code into machine code.

Sequence: The order in which instructions are executed in a program, one after another.
Variable: A named storage location in memory that holds a value which can change.
Assignment: The act of giving a value to a variable using the equals sign (=).
Data type: The kind of data a variable holds, such as integer, string, or boolean.
Input: Data entered into a program, often from the user via keyboard.
Output: Data displayed by a program, often on the screen.
Integer: A whole number (positive, negative, or zero) without a decimal point.
String: A sequence of characters, such as text, enclosed in quotes.
Boolean: A data type that has only two values: True or False.
Concatenation: Joining two or more strings together to form a single string.
Debugging: The process of finding and fixing errors (bugs) in a program.
High-level language: A programming language that is easier for humans to read and write than machine code.
Compiler: A program that translates high-level language code into machine code that a computer can execute.

Thẻ ghi nhớ

What is a sequence in programming?

A sequence is the order in which instructions are executed, one after another, in a program.

What is a variable?

A variable is a named storage location in memory that holds a value which can change during program execution.

How do you assign a value to a variable in Python?

Use the assignment operator '='. For example: age = 15.

What are the three basic data types mentioned?

Integer (whole numbers), string (text), and boolean (True/False).

What is an integer?

An integer is a whole number, positive or negative, without a fractional part, e.g., 42 or -7.

What is a string?

A string is a sequence of characters, such as letters, digits, and symbols, enclosed in quotes, e.g., 'Hello'.

What is a boolean?

A boolean is a data type with two possible values: True or False, often used in conditions.

How do you take input from the user in Python?

Use the input() function. For example: name = input('Enter your name: ').

How do you produce output in Python?

Use the print() function. For example: print('Hello, world!').

What is the result of the expression 7 + 3×2?

13, because multiplication is performed before addition (operator precedence).

How do you concatenate two strings in Python?

Use the '+' operator. For example: 'Hello' + ' ' + 'World' gives 'Hello World'.

What is a high-level programming language?

A language that is easier for humans to read and write than machine code, such as Python.

What is debugging?

Debugging is the process of finding and fixing errors (bugs) in a program.

What is an algorithm?

An algorithm is a step-by-step set of instructions to solve a problem or perform a task.

What is the purpose of comments in code?

Comments are notes in the code that are ignored by the computer but help humans understand the program.

What is the difference between a variable and a constant?

A variable's value can change, while a constant's value stays the same once set.

What does the input() function return?

It returns the user's input as a string.

How do you convert a string to an integer in Python?

Use the int() function. For example: int('42') gives 42.

What is a syntax error?

A syntax error occurs when the code does not follow the rules of the programming language, so it cannot be run.

What is a runtime error?

A runtime error happens while the program is running, such as dividing by zero.

What is a logic error?

A logic error is a mistake in the program's logic that causes incorrect results, even though the program runs without crashing.

What is the order of operations in Python?

Python follows standard arithmetic precedence: parentheses, exponents, multiplication/division, addition/subtraction.

What is the purpose of the '=' operator?

It assigns a value to a variable. For example, x = 5 stores 5 in x.

What is the difference between '=' and '==' in Python?

'=' is assignment, while '==' is a comparison operator that checks if two values are equal.

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