ToLower, ToUpper

There are lowercase and uppercase letters. To change from one to the other, we can use functions from the strings package in Go.

The strings.ToLower and ToUpper funcs have the expected results. They do not change characters like digits, spaces, or punctuation. Title() capitalizes all words.

ToLower example

Let us begin with strings.ToLower. We have a string literal with the value of "Name." When we call ToLower, a new string is returned.

package main

import (
    "fmt"
    "strings"
)

func main() {

    value := "Name"

    // Convert to lowercase.
    valueLower := strings.ToLower(value)

    fmt.Println("BEFORE:", value)
    fmt.Println("AFTER: ", valueLower)
}
BEFORE: Name
AFTER:  name

ToUpper example

The ToUpper func works in the same way as ToLower. It returns a new, copied version of the string argument that has lowercase chars changed to uppercase ones.

package main

import (
    "fmt"
    "strings"
)

func main() {

    value := "Dot Net Perls"

    // Use ToUpper.
    valueUpper := strings.ToUpper(value)

    fmt.Println("BEFORE:", value)
    fmt.Println("AFTER: ", valueUpper)
}
BEFORE: Dot Net Perls
AFTER:  DOT NET PERLS

Title

The strings package provides ways to change the case of characters. Here we apply title-casing to a string with the Title func. The result is a properly-capitalized string.

package main

import (
    "fmt"
    "strings"
)

func main() {
    name := "the apology"

    // Capitalize this string.
    result := strings.Title(name)
    fmt.Println(result)
}
The Apology

For real-world programs in Go, we often need methods like strings.ToLower and ToUpper. These can help us simplify our programs (as by using only lowercase-based logic).