Output using fmt.Println in Go

Introduction

We use fmt.Println to show messages or results on the screen. It helps us see what our program is doing.

To display a greeting message to the user.

To show the result of a calculation.

To print debugging information while writing code.

To output text or numbers during program execution.

To separate lines of output clearly.

Syntax

Go

fmt.Println(value1, value2, ...)

fmt.Println prints each value separated by a space and adds a new line at the end.

You can print many values at once by separating them with commas.

Examples

Prints a simple text message.

Go

fmt.Println("Hello, world!")

Prints multiple numbers separated by spaces.

Go

fmt.Println(10, 20, 30)

Prints a label and the result of a calculation.

Go

fmt.Println("Sum:", 5+3)

Sample Program

This program prints three lines: a welcome message, a number with a label, and a goodbye message.

Go

package main

import "fmt"

func main() {
    fmt.Println("Welcome to Go programming!")
    fmt.Println("The answer is", 42)
    fmt.Println("Goodbye!")
}

Important Notes

Always import fmt to use fmt.Println.

fmt.Println automatically adds a new line after printing.

Use commas to print multiple values with spaces in between.

Summary

fmt.Println prints text or values to the screen with a new line.

You can print many things at once by separating them with commas.

It is useful for showing messages, results, or debugging information.

Practice

1. What does the fmt.Println function do in Go?

easy

A. Creates a new package

B. Reads input from the user

C. Declares a new variable

D. Prints text or values to the screen with a new line

Solution

1. Step 1: Understand the purpose of fmt.Println

   The function fmt.Println is used to display output on the screen, automatically adding a new line after the output.

2. Step 2: Differentiate from other functions

   It does not read input, declare variables, or create packages; it only prints output.

3. Final Answer:

   Prints text or values to the screen with a new line -> Option D

4. Quick Check:

   fmt.Println prints output with newline [OK]

Hint: Remember: println means print with a new line [OK]

Common Mistakes:

• Confusing fmt.Println with input functions
• Thinking it declares variables
• Assuming it creates packages

2. Which of the following is the correct way to print "Hello, Go!" using fmt.Println?

easy

A. fmt.Println("Hello, Go!")

B. fmt.Println('Hello, Go!')

C. fmt.Println(Hello, Go!)

D. fmt.Println(Hello Go)

Solution

1. Step 1: Check string syntax in Go

   Strings must be enclosed in double quotes " ". Single quotes ' ' are for single characters.

2. Step 2: Validate the options

   fmt.Println("Hello, Go!") uses double quotes correctly. Options A, B, and C either use single quotes or no quotes, which causes errors.

3. Final Answer:

   fmt.Println("Hello, Go!") -> Option A

4. Quick Check:

   Strings need double quotes in fmt.Println [OK]

Hint: Use double quotes for strings in fmt.Println [OK]

Common Mistakes:

• Using single quotes for strings
• Omitting quotes around text
• Forgetting commas inside print

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

package main
import "fmt"
func main() {
    fmt.Println("Go", "is", "fun")
}

medium

A. Go is fun

B. Goisfun

C. "Go is fun"

D. Go, is, fun

Solution

1. Step 1: Understand fmt.Println with multiple arguments

   When multiple values are separated by commas, fmt.Println prints them separated by spaces automatically.

2. Step 2: Analyze the output

   The output will be the words separated by spaces: Go is fun, followed by a new line.

3. Final Answer:

   Go is fun -> Option A

4. Quick Check:

   fmt.Println adds spaces between arguments [OK]

Hint: Multiple arguments print with spaces automatically [OK]

Common Mistakes:

• Expecting no spaces between words
• Thinking commas print literally
• Confusing output with quotes

4. Find the error in this Go code snippet:

package main
import "fmt"
func main() {
    fmt.Println("Hello" + "World")
}

medium

A. Syntax error due to missing comma

B. Runtime error because + can't join strings

C. No error, it prints HelloWorld

D. fmt.Println requires parentheses

Solution

1. Step 1: Check string concatenation in Go

   Using + between strings concatenates them without spaces.

2. Step 2: Verify fmt.Println usage

   fmt.Println can print the concatenated string without error.

3. Final Answer:

   No error, it prints HelloWorld -> Option C

4. Quick Check:

   String + concatenates; fmt.Println prints result [OK]

Hint: String + joins text; no comma needed inside fmt.Println [OK]

Common Mistakes:

• Thinking + causes syntax error in print
• Expecting space between Hello and World
• Confusing + with comma separator

5. You want to print the numbers 1, 2, and 3 on the same line separated by spaces using fmt.Println. Which code snippet achieves this correctly?

hard

A. fmt.Println(1 2 3)

B. fmt.Println("1", "2", "3")

C. fmt.Println("1" "2" "3")

D. fmt.Println(1 + 2 + 3)

Solution

1. Step 1: Understand printing multiple values

   Using commas in fmt.Println prints each argument separated by spaces automatically.

2. Step 2: Analyze each option

   fmt.Println(1 2 3) causes syntax error (missing commas or operators).
   fmt.Println("1" "2" "3") concatenates adjacent strings to "123" without spaces.
   fmt.Println("1", "2", "3") prints 1 2 3 with spaces.
   fmt.Println(1 + 2 + 3) prints 6.

3. Step 3: Choose the best for printing numbers as strings separated by spaces

   fmt.Println("1", "2", "3") prints the numbers as strings separated by spaces, exactly as requested.

4. Final Answer:

   fmt.Println("1", "2", "3") -> Option B

5. Quick Check:

   Separate strings with commas to print spaced values [OK]

Hint: Use commas to separate values for spaced output [OK]

Common Mistakes:

• Using + to join numbers (adds them instead)
• Printing a single string instead of separate values
• Confusing string and integer printing