How to use for and foreach loop in Golang?
Last Updated :
28 Apr, 2025
There is only one looping construct in Golang, and that is the for loop. The for loop in Golang has three components, which must be separated by semicolons (;), those are:
- The initialization statement: which is executed before the first iteration. e.g. i := 0
- The condition expression: which is executed just before every iteration. e.g. i < 5
- The Post statement: which is executed at the end of every iteration. e.g. i++
There is no need for any parentheses for enclosing those three components, but to define a block we must use braces { }.
for i := 0 ; i < 5 ; i++{
// statements to execute......
}
The initialization and post statements are optional.
i:=0
for ; i < 5;{
i++
}
You can use for loop as while loop in Golang. Just drop all the semicolons.
i := 0
for i < 5 {
i++
}
Infinite Loop: If there is no condition statement, the loop becomes an infinite loop.
for {
}
Example:
Go
package main
import "fmt"
// function to print numbers 0
// to 9 and print the sum of 0 to 9
func main() {
// variable to store the sum
sum := 0
// this is a for loop which runs from 0 to 9
for i := 0; i < 10; i++ {
// printing the value of
// i : the iterating variable
fmt.Printf("%d ", i)
// calculating the sum
sum += i
}
fmt.Printf("\nsum = %d", sum)
}
Output:
0 1 2 3 4 5 6 7 8 9
sum = 45
In Golang there is no foreach loop instead, the for loop can be used as "foreach". There is a keyword range, you can combine for and range together and have the choice of using the key or value within the loop.Syntax:
for <key>, <value> := range <container>{
}
Here,
- key and value: It can be any variable you want to choose.
- container: It can be any variable which is an array, list, map, etc.
Example 1:
Go
package main
import "fmt"
// Driver function to show the
// use of for and range together
func main() {
// here we used a map of integer to string
mapp := map[int]string{1: "one", 2: "two", 3: "three"}
// integ act as keys of mapp
// spell act as the values of
// mapp which is mapped to integ
for integ, spell := range mapp {
// using integ and spell as
// key and value of the map
fmt.Println(integ, " = ", spell)
}
}
Output:
1 = one
2 = two
3 = three
Example 2:
Go
package main
import "fmt"
// Driver function to show the
// use of for and range together
func main() {
// declaring an array of integers
arra := []int{1, 2, 3, 4}
// traversing through the array
for index, itr := range arra {
// the key or value variables
// used in for syntax
// depends on the container.
// If its an array or list,
// the key refers to the index...
fmt.Print(index, " : ", itr, "\n")
}
// if we use only one
// variable in the for loop,
// it by default refers to
// the value in the container.
for itr := range arra {
fmt.Print(it, " ")
}
}
Output:
0 : 1
1 : 2
2 : 3
3 : 4
1 2 3 4