The `fmt` package in Go

fmt Package

The fmt package provides functions for formatted I/O, string formatting, and error handling. It is part of the standard library in Go.

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Output Functions

1. fmt.Println

Prints values with a newline at the end.

package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
    fmt.Println("Go is awesome!")
}

Output:

Hello, World!
Go is awesome!

2. fmt.Print

Prints values without adding a newline.

package main

import "fmt"

func main() {
    fmt.Print("Hello, ")
    fmt.Print("World!")
}

Output:

Hello, World!

3. fmt.Printf

Prints formatted values using format specifiers.

package main

import "fmt"

func main() {
    name := "Areen"
    age := 16
    fmt.Printf("My name is %s and I am %d years old.\n", name, age)
}

Output:

My name is Areen and I am 16 years old.

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String Formatting Functions

4. fmt.Sprintln

Formats values and returns them as a string with a newline.

package main

import "fmt"

func main() {
    str := fmt.Sprintln("Hello,", "World!")
    fmt.Print(str)
}

Output:

Hello, World!

5. fmt.Sprint

Formats values and returns them as a string without a newline.

package main

import "fmt"

func main() {
    str := fmt.Sprint("Hello, ", "World!")
    fmt.Print(str)
}

Output:

Hello, World!

6. fmt.Sprintf

Formats values and returns them as a formatted string.

package main

import "fmt"

func main() {
    name := "Areen"
    age := 16
    str := fmt.Sprintf("My name is %s and I am %d years old.", name, age)
    fmt.Println(str)
}

Output:

My name is Areen and I am 16 years old.

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Error Formatting

7. fmt.Errorf

Creates a formatted error message of type error.

package main

import (
    "errors"
    "fmt"
)

func main() {
    err := fmt.Errorf("this is an error: %w", errors.New("underlying issue"))
    fmt.Println(err)
}

Output:

this is an error: underlying issue

---

Input Functions

8. fmt.Scan

Reads space-separated values from standard input.

package main

import "fmt"

func main() {
    var name string
    fmt.Print("Enter your name: ")
    fmt.Scan(&name)
    fmt.Println("Hello,", name)
}

Example Input:

Enter your name: Areen

Output:

Hello, Areen

9. fmt.Scanln

Reads values from standard input until a newline is encountered.

package main

import "fmt"

func main() {
    var name string
    fmt.Print("Enter your name: ")
    fmt.Scanln(&name)
    fmt.Println("Hello,", name)
}

Example Input:

Enter your name: Areen

Output:

Hello, Areen

10. fmt.Scanf

Reads formatted input from standard input.

package main

import "fmt"

func main() {
    var name string
    var age int
    fmt.Print("Enter your name and age: ")
    fmt.Scanf("%s %d", &name, &age)
    fmt.Printf("Hello %s, you are %d years old.\n", name, age)
}

Example Input:

Enter your name and age: Areen 16

Output:

Hello Areen, you are 16 years old.

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These examples showcase how to use each function in the fmt package. Let me know if you want further clarification!