fmt.Fscanln() Function in Golang With Examples

In Go language, fmt package implements formatted I/O with functions analogous to C’s printf() and scanf() function. The fmt.Fscanln() function in Go language scans the specified text, read from r and then stores successive space-separated values into successive arguments. This function stops scanning at a newline and after the final item, there must be a newline or EOF. Moreover, this function is defined under the fmt package. Here, you need to import the “fmt” package in order to use these functions.

Syntax:

func Fscanln(r io.Reader, a ...interface{}) (n int, err error)

Parameters: This function accepts two parameters which are illustrated below:

• r io.Reader: This parameter contains the scanned specified texts.
• a …interface{}: These parameters are accepting each specified elements.

Returns: It returns the number of items successfully scanned.

Example 1:

// Golang program to illustrate the usage of
// fmt.Fscanln() function

// Including the main package
package main

// Importing fmt, io and strings
import (
    "fmt"
    "io"
    "strings"
)

// Calling main
func main() {

    // Declaring list of strings,
    // integers and float value
    s := `gfg 9`

    // Calling NewReader() function for
    // reading each elements of the list
    // and then it place it into "r"
    r := strings.NewReader(s)

    // Declaring different types of variables
    var a string
    var b int

    for {

        // Calling Fscanln() function
        n, err := fmt.Fscanln(r, &a, &b)

        // Checking returned error is
        // end of the line (EOF) or not
        if err == io.EOF {
            break
        }

        // Checking if there is any error
        if err != nil {
            panic(err)
        }

        // Printing the number of items successfully
        // scanned and each elements too
        fmt.Printf("%d: %s, %d", n, a, b)
    }
}

Output:

2: gfg, 9

Example 2:

// Golang program to illustrate the usage of
// fmt.Fscanln() function

// Including the main package
package main

// Importing fmt, io and strings
import (
    "fmt"
    "io"
    "strings"
)

// Calling main
func main() {

    // Declaring list of strings,
    // integers and float value
    s := `gfg 9 true 5.78`

    // Calling NewReader() function for
    // reading each elements of the list
    // and then it place it into "r"
    r := strings.NewReader(s)

    // Declaring different types of variables
    var a string
    var b int
    var c bool
    var d float32

    for {

        // Calling Fscanln() function
        n, err := fmt.Fscanln(r, &a, &b, &c, &d)

        // Checking returned error is
        // end of the line (EOF) or not
        if err == io.EOF {
            break
        }

        // Checking if there is any error
        if err != nil {
            panic(err)
        }

        // Printing the number of items successfully
        // scanned and each elements too
        fmt.Printf("%d: %s, %d, %t, %g", n, a, b, c, d)
    }
}

Output:

4: gfg, 9, true, 5.78