Nested loops in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a nested loop in Go?

A nested loop is a loop inside another loop. The inner loop runs completely for each iteration of the outer loop.

beginner

How many times will the inner loop run in this code?<br>

for i := 0; i < 3; i++ {
  for j := 0; j < 2; j++ {
    fmt.Println(i, j)
  }
}

The inner loop runs 2 times for each of the 3 outer loop iterations, so 3 * 2 = 6 times total.

beginner

Why use nested loops?

Nested loops help when you want to work with multi-dimensional data, like grids or tables, by repeating actions inside another repeated action.

intermediate

What happens if the inner loop has a break statement?

The break stops only the inner loop. The outer loop continues to the next iteration.

beginner

How can you print a 3x3 grid of stars (*) using nested loops in Go?

Use an outer loop for rows and an inner loop for columns, printing '*' each time. After inner loop ends, print a new line.

In Go, what does a nested loop mean?

A Two loops running at the same time

B A loop that runs only once

C A loop inside another loop

D A loop with no body

A nested loop is when one loop is placed inside another loop's body.

How many times will the inner loop run in this code?<br>

for i := 0; i < 4; i++ {
  for j := 0; j < 3; j++ {
    // inner loop body
  }
}

A 3 times

B 4 times

C 7 times

D 12 times

The inner loop runs 3 times for each of the 4 outer loop iterations, so 4 * 3 = 12 times.

What will happen if you put a break statement inside the inner loop?

A Only the inner loop stops

B Both loops stop immediately

C Only the outer loop stops

D Nothing happens

The break stops only the loop where it is placed, so only the inner loop stops.

Which of these is a good use case for nested loops?

A Working with a grid or table of data

B Calculating the sum of numbers

C Printing a list of names

D Reading a single file

Nested loops are useful for working with multi-dimensional data like grids or tables.

What is the output of this Go code?<br>

for i := 1; i <= 2; i++ {
  for j := 1; j <= 2; j++ {
    fmt.Print(i * j, " ")
  }
  fmt.Println()
}

A 1 1 \n 2 2

B 1 2 \n 2 4

C 1 2 3 \n 4 5 6

D 2 4 \n 2 4

The inner loop prints i*j for j=1 and 2, then a new line. So first line: 1*1=1, 1*2=2; second line: 2*1=2, 2*2=4.

Explain what nested loops are and give a simple example in Go.

Think about a loop inside another loop and how many times the inner loop runs.

Describe a real-life situation where nested loops would be useful.

Imagine rows and columns in a spreadsheet.