Learn Golang Tutorials - foreach loop with range keyword examples

In this blog post, We are going to learn for each loop with range in go language with example

Golang for each loop

the foreach loop is a for loop with range keyword. It is used iterate each element from Array, Slice, Map, and Strings. This is always useful to iterate the elements of a data structure without getting the length of data structure Syntax of the for with range loop is as follows

for key, value := range collection{  
// body  
}

During an iteration of the collection, each iteration contains key or index, value or element at index.
Few key points for loop with range keywords

This is used to iterate elements of a collections types
Each iteration data contains two parts, One is key or index, the second is a value or an element at index
The iterated elements order is not ordered or preserved in a collections
use the key as _ for retrieving values during array iteration
for array and slice, the first element is an index, the second value is an element at index position for each iteration
if the array or slice is empty, It returns nothing

For each array range iteration example

Below is an example for iterate the array of numbers

package main  
  
import "fmt"  
  
func main() {  
	// Iterate numeric array  
	numbers := [3]int{6, 9, 3}  
	for key, value := range numbers {  
		fmt.Printf("%d = %d\n", key, value)  
	}  
}

Output is

0 = 6  
1 = 9  
2 = 3

For array iteration, the First variable for iteration value can be passed _

func main() {  
	// Iterate numeric array  
	numbers := [3]int{6, 9, 3}  
	for _, value := range numbers {  
		fmt.Printf("%d ", value)  
	}  
}

Output is

6 9 3

another way is using the index parameter of iteration value to traverse the elements of the array

func main() {  
	// Iterate numeric array  
	numbers := [3]int{6, 9, 3}  
	for i := range numbers {  
		fmt.Printf("%d ", numbers[i])  
	}  
}

Output is

6 9 3

Iteration examples with range keyword

The below example covers the following things

Iterate elements in Numeric Array
Loop elements in String Array
Iterate elements in Unicode characters of a string
Iterate elements in Map

package main  
  
import "fmt"  
  
func main() {  
  
	// Create Numeric array  
	numbers := [3]int{6, 9, 3}  
	// Iterate numeric array  
	for key, value := range numbers {  
		fmt.Printf("%d = %d\n", key, value)  
	}  
	// Create String array  
	strs := [3]string{"one", "two", "three"}  
	// Iterate String array  
	for key, value := range strs {  
		fmt.Printf("%d = %s\n", key, value)  
	}  
  
	/* create a map*/  
	emps := map[string]string{"1": "John", "2": "Franc", "3": "Kiran"}  
  
	/* Iterate map using keys*/  
	for emp := range emps {  
		fmt.Println("Emp Id: ", emp, " Name: ", emps[emp])  
	}  
	/* Iterate Unicode charactes of a String*/  
	for index, character := range "本語日" {  
		fmt.Printf("%#U  position %d\n", character, index)  
	}  
  
}

The output of the above program code is

0 = 6  
1 = 9  
2 = 3  
0 = one  
1 = two  
2 = three  
Emp Id:  1  Name:  John  
Emp Id:  2  Name:  Franc  
Emp Id:  3  Name:  Kiran  
U+672C '本'  position 0  
U+8A9E '語'  position 3  
U+65E5 '日'  position 6

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