base64.DecodeString() Function in Golang With Examples

Go language provides inbuilt support for base64 encoding/decoding and has functions that could be used to perform operations on the given data using the base64 package. This package provides DecodeString() function which is used to decode a base64 string to its plaintext form. It supports decoding using both standard and URL compatible base64 standards.

Syntax:

func (enc *Encoding) DecodeString(s string) ([]byte, error)

The Encoding type used with the decoder has 4 variations:

• StdEncoding: It is the standard encoding to be used as defined by the RFC 4648 standard.
• RawStdEncoding: It is the standard encoding to be used as defined by the RFC 4648 standard, except that the padding characters are omitted.
• URLEncoding: It is the URL encoding to be used as defined by the RFC 4648 standard. It is typically used for encoding URLs and filenames.
• RawURLEncoding:It is the URL encoding to be used as defined by the RFC 4648 standard. It is typically used for encoding URLs and filenames, except that the padding characters are omitted.

Return Value: It returns the bytes represented by the given base64 string.

Below programs illustrate the DecodeString() function:

Example 1:

// Golang program to illustrate
// the base64.DecodeString() Function
package main

import (
    "encoding/base64"
    "fmt"
)

func main() {

    // taking a string
    givenString := "R2Vla3Nmb3JHZWVrcw=="

    // using the function
    decodedString, err := base64.StdEncoding.DecodeString(givenString)
    if err != nil {
        fmt.Println("Error Found:", err)
        return
    }

    fmt.Print("Decoded Bytes: ")
    fmt.Println(decodedString)

    fmt.Print("Decoded String: ")
    fmt.Println(string(decodedString))
}

Output:

Decoded Bytes: [71 101 101 107 115 102 111 114 71 101 101 107 115]
Decoded String: GeeksforGeeks

Example 2:

// Golang program to illustrate
// the base64.DecodeString() Function
package main

import (
    "encoding/base64"
    "fmt"
)

func main() {

    // taking a string
    givenString := "aHR0cHM6Ly93d3cuZ2Vla3Nmb3JnZWVrcy5vcmcv"

    // using the function
    decodedString, err := base64.URLEncoding.DecodeString(givenString)
    if err != nil {
        fmt.Println("Error Found:", err)
        return
    }

    fmt.Print("Decoded Bytes: ")
    fmt.Println(decodedString)

    fmt.Print("Decoded String: ")
    fmt.Println(string(decodedString))
}

Output:

Decoded Bytes: [104 116 116 112 115 58 47 47 119 119 119 46 103 101 101 107 115 102 111 114 103 101 101 107 115 46 111 114 103 47]
Decoded String: https://www.geeksforgeeks.org/