Strings In Go Lang

When we say advanced data type it means that we are learning about the another data types that exist in GO lang but required some extra knowledge to understand.

String

A string is a set of characters it can be of a single character or can be of a multiple characters. In golang we write sting inside `` ( back quote ) or “” ( double quote) for example string1 and "s" are two different strings in go lang '' is not used with strings It’s a separate data type that can hold a single character for more checkout this post Variables and Data Types.

Here is the visual representation of a String:

In a string we have index value of each character (we can call them rune also as they are a single character ) and we can access them using there index value for example 0 has V it can be written as string_name[index_value].

Here is an example for the same:

var1 := "test string"   // True
var2 := 'test string'   // Error
var3 := `test string`   // True

Output with String

package main

import ("fmt")

func main(){

	name := "Vipin"

	fmt.Println(name)
	
	fmt.Println("Vipin Kumar")
	
	fmt.Printf("%s", "New String")
}

Input with String

package main

import "fmt"

func main() {

	var name string

	fmt.Printf("Enter Your Name: ")
	fmt.Scan(&name)

	fmt.Printf("Hello %s!\n", name)
}

There is a inbuilt function in Go to find the length of a sting we will study about functions and modules soon for now let’s see how len() works.

So len() function in GO lang gives you the length of the sting.

For Example:

package main

import ("fmt")

func main() {

	test_str := "vipin"

	fmt.Println( len(test_str) )

	fmt.Println( len("Vipin Kumar") )
}

Output:

go run Day12/len.go 
5
11

There is 1 more method we will be using DecodeRuneInString it’s from library unicode/utf8 this method covert a rune into a string.

Example:

Looping Over A String

Here are 2 most common ways to loop on a string one using the range and another is using normal for loop.

For Loop Without Range On Strings

We can get the length of the string usine len function then we can use for loop to iterate from 0 to length - 1 because string indexing starts from 0. let’s say we have a string of length 5 so it’s index values are 0,1,2,3,4.

Example:

package main

import "fmt"

func main() {
	
	name := "Vipin Kumar"

	length := len(name)

	for iterator := 0 ; iterator < length ; iterator += 1 {

		fmt.Printf( "Index Value %d has character %c.\n", iterator, name[iterator] )

	}

}

Output:

go run Day12/forwithoutrange.go 
Index Value 0 has character V.
Index Value 1 has character i.
Index Value 2 has character p.
Index Value 3 has character i.
Index Value 4 has character n.
Index Value 5 has character  .
Index Value 6 has character K.
Index Value 7 has character u.
Index Value 8 has character m.
Index Value 9 has character a.
Index Value 10 has character r.

For Loop With Range On Strings

We can get the length of the string usine len function then we can use for loop to iterate from 0 to length - 1 because string indexing starts from 0. let’s say we have a string of length 5 so it’s index values are 0,1,2,3,4.

Example:

package main

import "fmt"

func main() {
	
	name := "Vipin Kumar"

	for str := range name {

		fmt.Printf( "Index %d has value %c.\n", str, name[str]  )

	}

}

Output:

go run Day12/forwithoutrange.go 
Index Value 0 has character V.
Index Value 1 has character i.
Index Value 2 has character p.
Index Value 3 has character i.
Index Value 4 has character n.
Index Value 5 has character  .
Index Value 6 has character K.
Index Value 7 has character u.
Index Value 8 has character m.
Index Value 9 has character a.
Index Value 10 has character r.

Strings In Go Lang are immutable it means that you can not update the value of a string after initialization.

Doc was written in this livestream [Learn Go Day 12] and [Learn Go Day 14]