Basic input concepts in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read a string input from the user.

Go

var name string
fmt.Print("Enter your name: ")
fmt.Scanln([1])
fmt.Println("Hello,", name)

Drag options to blanks, or click blank then click option'

A&name

Bname

C*name

Dname&

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the variable without & causes a runtime error.

Using *name is invalid because name is not a pointer.

In Go, to read input into a variable, you must pass its address using &.

2fill in blank

medium

Complete the code to read an integer input from the user.

Go

var age int
fmt.Print("Enter your age: ")
fmt.Scanln([1])
fmt.Println("You are", age, "years old")

Drag options to blanks, or click blank then click option'

A&age

B*age

Cage

Dage&

Attempts:

3 left

💡 Hint

Common Mistakes

Passing age without & causes input not to be stored.

Using *age is invalid since age is not a pointer.

Use &age to pass the address of the integer variable to fmt.Scanln.

3fill in blank

hard

Fix the error in reading a float input from the user.

Go

var price float64
fmt.Print("Enter price: ")
fmt.Scanln([1])
fmt.Printf("Price: %.2f\n", price)

Drag options to blanks, or click blank then click option'

Aprice

Bprice&

C*price

D&price

Attempts:

3 left

💡 Hint

Common Mistakes

Passing price without & causes the value not to be stored.

Using *price is invalid because price is not a pointer.

To read input into a float64 variable, pass its address with &.

4fill in blank

hard

Fill both blanks to read two inputs: a string and an integer.

Go

var name string
var age int
fmt.Print("Enter name and age: ")
fmt.Scanln([1], [2])
fmt.Println(name, age)

Drag options to blanks, or click blank then click option'

A&name

Bname

C&age

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Passing variables without & causes input not to be stored.

Mixing & and non-& variables causes errors.

Use &name and &age to pass addresses of variables to fmt.Scanln for input.

5fill in blank

hard

Fill all three blanks to read a string, an integer, and a float input.

Go

var name string
var age int
var height float64
fmt.Print("Enter name, age, and height: ")
fmt.Scanln([1], [2], [3])
fmt.Println(name, age, height)

Drag options to blanks, or click blank then click option'

A&name

B&age

C&height

Dheight

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting & causes input not to be stored.

Passing a variable without & among others causes runtime errors.

Pass the addresses of all variables using & to read multiple inputs with fmt.Scanln.

Practice

1. What is the main purpose of using input functions in Go programs?

easy

A. To get information from the user during program execution

B. To print messages on the screen

C. To declare variables

D. To create new functions

Solution

1. Step 1: Understand input function role

   Input functions allow the program to receive data from the user while it runs.

2. Step 2: Differentiate input from output

   Printing messages is output, not input. Declaring variables or creating functions are unrelated.

3. Final Answer:

   To get information from the user during program execution -> Option A

4. Quick Check:

   Input = get user data [OK]

Hint: Input means getting data from user, not showing it [OK]

Common Mistakes:

• Confusing input with output (printing)
• Thinking input declares variables
• Mixing input with function creation

2. Which of the following is the correct way to read a single word input from the user in Go?

easy

A. fmt.Println(variable)

B. fmt.Scanln(&variable)

C. bufio.NewReader(os.Stdin).ReadString()

D. var input string

Solution

1. Step 1: Identify input reading functions

   fmt.Scanln reads a single word or token from user input into a variable.

2. Step 2: Eliminate other options

   fmt.Println prints output, bufio.NewReader reads full lines, and declaring a variable alone doesn't read input.

3. Final Answer:

   fmt.Scanln(&variable) -> Option B

4. Quick Check:

   Single word input uses fmt.Scanln [OK]

Hint: Use fmt.Scanln for simple word input [OK]

Common Mistakes:

• Using fmt.Println to read input
• Confusing bufio.NewReader with Scanln for single words
• Forgetting to pass variable address with &

3. What will be the output of this Go code snippet?

var name string
fmt.Print("Enter name: ")
fmt.Scanln(&name)
fmt.Println("Hello,", name)

If the user types: John and presses Enter.

medium

A. Hello,

B. Error: missing input

C. Enter name: John

D. Hello, John

Solution

1. Step 1: Understand input reading

   fmt.Scanln reads the word 'John' into variable name.

2. Step 2: Understand output printing

   fmt.Println prints "Hello," followed by the value of name, which is "John".

3. Final Answer:

   Hello, John -> Option D

4. Quick Check:

   Input 'John' prints 'Hello, John' [OK]

Hint: Scanln reads input; println shows it back [OK]

Common Mistakes:

• Expecting input prompt to print again
• Thinking Scanln reads empty string
• Confusing output with input prompt

4. What is wrong with this Go code for reading a full line input?

var input string
reader := bufio.NewReader(os.Stdin)
input, _ = reader.ReadString('\n')
fmt.Println(input)

medium

A. It does not import the bufio and os packages

B. ReadString does not read until newline

C. input variable is declared twice causing error

D. fmt.Println cannot print strings

Solution

1. Step 1: Check package imports

   bufio and os packages must be imported to use bufio.NewReader and os.Stdin.

2. Step 2: Verify variable declaration

   input is declared once and assigned, which is correct. ReadString reads until newline correctly. fmt.Println can print strings.

3. Final Answer:

   It does not import the bufio and os packages -> Option A

4. Quick Check:

   Missing imports cause errors [OK]

Hint: Always import bufio and os for buffered input [OK]

Common Mistakes:

• Forgetting to import required packages
• Redeclaring variables with := after declaration
• Assuming ReadString reads partial input

5. You want to read a user's full name including spaces in Go. Which approach correctly reads and cleans the input to remove the trailing newline?

hard

A. Use fmt.Println to read input

B. Use fmt.Scanln(&name) only

C. Use bufio.NewReader(os.Stdin).ReadString('\n') and strings.TrimSpace()

D. Use fmt.Scanf("%s", &name)

Solution

1. Step 1: Identify method for full line input

   bufio.NewReader with ReadString('\n') reads the entire line including spaces.

2. Step 2: Remove trailing newline

   strings.TrimSpace removes extra spaces and newline characters from input.

3. Final Answer:

   Use bufio.NewReader(os.Stdin).ReadString('\n') and strings.TrimSpace() -> Option C

4. Quick Check:

   Full line input + trim newline = Use bufio.NewReader(os.Stdin).ReadString('\n') and strings.TrimSpace() [OK]

Hint: Use bufio + TrimSpace for full line input [OK]

Common Mistakes:

• Using Scanln which stops at space
• Using Scanf with %s reads only one word
• Trying to read input with Println