Why variables are needed in Go - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable named age with value 30.

Go

var age [1] = 30

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

Abool

Bstring

Cint

Dfloat64

Attempts:

3 left

💡 Hint

Common Mistakes

Using string type for a number.

Forgetting to specify the type.

In Go, int is used to declare integer variables like age which holds whole numbers.

2fill in blank

medium

Complete the code to assign the value 100 to the variable score.

Go

var score int
score [1] 100

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

A=

B==

C:=

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using == instead of = for assignment.

Using := when variable is already declared.

The single equals sign = is used to assign a value to a variable in Go.

3fill in blank

hard

Fix the error in the code to declare and assign variable name with value "Alice".

Go

var name [1] = "Alice"

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

Aint

Bfloat64

Cbool

Dstring

Attempts:

3 left

💡 Hint

Common Mistakes

Using numeric types for text variables.

Omitting the type declaration.

The variable name holds text, so its type must be string.

4fill in blank

hard

Fill both blanks to declare a variable height of type float64 and assign it the value 1.75.

Go

var height [1] [2] 1.75

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

Afloat64

B=

C:=

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using int type for decimal numbers.

Using := when variable is declared with var.

Use float64 for decimal numbers and = to assign the value.

5fill in blank

hard

Fill all three blanks to declare and assign a variable isActive of type bool with value true.

Go

var [1] [2] [3] true

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

AisActive

Bbool

C=

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using int type for boolean values.

Forgetting to assign a value.

Declare the variable name isActive, type bool, and assign it true using =.

Practice

1. Why do we need variables in Go programming?

easy

A. To write comments in the code

B. To make the program run faster

C. To store and reuse data during program execution

D. To create functions

Solution

1. Step 1: Understand the purpose of variables

   Variables hold data that can be used and changed while the program runs.

2. Step 2: Identify the correct use of variables

   Variables help keep data organized and allow reuse without rewriting values.

3. Final Answer:

   To store and reuse data during program execution -> Option C

4. Quick Check:

   Variables store data = A [OK]

Hint: Variables hold data to use later in code [OK]

Common Mistakes:

• Thinking variables speed up the program
• Confusing variables with comments
• Believing variables create functions

2. Which of the following is the correct way to declare a variable in Go?

easy

A. x := int 10

B. var x int = 10

C. int x = 10

D. declare x = 10

Solution

1. Step 1: Recall Go variable declaration syntax

   In Go, variables can be declared using 'var' keyword followed by name, type, and value.

2. Step 2: Check each option's syntax

   var x int = 10 uses 'var x int = 10' which is correct. Others do not follow Go syntax.

3. Final Answer:

   var x int = 10 -> Option B

4. Quick Check:

   Go variable declaration = var x int = 10 [OK]

Hint: Use 'var' keyword or ':=' to declare variables [OK]

Common Mistakes:

• Using C-style declarations like 'int x = 10'
• Mixing ':=' with type keyword incorrectly
• Using non-Go keywords like 'declare'

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

package main
import "fmt"
func main() {
  var count int = 5
  count = count + 3
  fmt.Println(count)
}

medium

A. 8

B. Compilation error

C. 0

D. 5

Solution

1. Step 1: Understand variable initialization and update

   Variable 'count' starts at 5, then 3 is added, so count becomes 8.

2. Step 2: Predict the printed output

   The program prints the updated value of count, which is 8.

3. Final Answer:

   8 -> Option A

4. Quick Check:

   5 + 3 = 8 [OK]

Hint: Add values stored in variables to find output [OK]

Common Mistakes:

• Assuming variable value stays 5
• Thinking output is zero by default
• Expecting a syntax error

4. Find the error in this Go code snippet:

package main
import "fmt"
func main() {
  x := 10
  var x int = 20
  fmt.Println(x)
}

medium

A. Missing semicolon after declaration

B. No error, code runs fine

C. Incorrect import statement

D. Variable redeclaration error

Solution

1. Step 1: Analyze variable declarations

   The code declares 'x' twice in the same scope: once with ':=' and once with 'var'.

2. Step 2: Understand Go's redeclaration rules

   Go does not allow redeclaring a variable with the same name in the same scope, causing an error.

3. Final Answer:

   Variable redeclaration error -> Option D

4. Quick Check:

   Redeclaring variable in same scope = error [OK]

Hint: Don't declare same variable twice in one scope [OK]

Common Mistakes:

• Thinking missing semicolon causes error
• Believing import statement is wrong
• Assuming code runs without error

5. You want to store a user's age and then increase it by 1 in Go. Which code correctly uses variables to do this?

hard

A. var age int = 30
age = age + 1
fmt.Println(age)

B. age := 30
age := age + 1
fmt.Println(age)

C. var age = "30"
age = age + 1
fmt.Println(age)

D. var age int
age = "31"
fmt.Println(age)

Solution

1. Step 1: Check variable declaration and type

   var age int = 30 age = age + 1 fmt.Println(age) declares 'age' as int and initializes it with 30, which is correct.

2. Step 2: Verify increment operation and printing

   var age int = 30 age = age + 1 fmt.Println(age) correctly adds 1 to 'age' and prints the result. Other options have redeclaration or type errors.

3. Final Answer:

   var age int = 30 age = age + 1 fmt.Println(age) -> Option A

4. Quick Check:

   Declare int, add 1, print = var age int = 30 age = age + 1 fmt.Println(age) [OK]

Hint: Declare once, update value with '=' operator [OK]

Common Mistakes:

• Redeclaring variable with ':=' twice
• Mixing string and int types
• Assigning string to int variable