1for initialization ; condition ; counter { 
2	//loop codes 
3} 

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6	sum := 0
 7	for i := 1; i < 10; i++ {
 8		sum += i
 9	}
10
11	fmt.Println(sum)
12}

1$ go run main.go
245

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6	i := 0
 7	for i < 10 {
 8		fmt.Println(i)
 9		i++
10	}
11}

 1$ go run main.go
 20
 31
 42
 53
 64
 75
 86
 97
108
119

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6	sum := 0
 7	for {
 8		sum++
 9	}
10
11	fmt.Println("this line will never execute")
12}

1for index, value := range slice/array {}

1for key, value := range map {}

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6    letters := []string{"a", "b", "c"}
 7
 8    //With index and value
 9    fmt.Println("Both Index and Value")
10    for i, letter := range letters {
11        fmt.Printf("Index: %d Value:%s\n", i, letter)
12    }
13    
14	//Only value
15    fmt.Println("\nOnly value")
16    for _, letter := range letters {
17        fmt.Printf("Value: %s\n", letter)
18    }
19}

 1$ go run main.go
 2Both Index and Value
 3Index: 0 Value:a
 4Index: 1 Value:b
 5Index: 2 Value:c
 6
 7Only value
 8Value: a
 9Value: b
10Value: c

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6    letters := []string{"a", "b", "c"}
 7
 8    fmt.Println("\nOnly letter")
 9    for i := range letters {
10        fmt.Printf("letter: %s\n", letters[i])
11    }
12}

1$go run main.go
2Only letter
3letter: a
4letter: b
5letter: c

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6    sample := map[string]string{
 7        "a": "x",
 8        "b": "y",
 9    }
10
11    //Iterating over all keys and values
12    fmt.Println("Both Key and Value")
13    for k, v := range sample {
14        fmt.Printf("key :%s value: %s\n", k, v)
15    }
16
17    //Iterating over only keys
18    fmt.Println("\nOnly keys")
19    for k := range sample {
20        fmt.Printf("key :%s\n", k)
21    }
22
23    //Iterating over only values
24    fmt.Println("\nOnly values")
25    for _, v := range sample {
26        fmt.Printf("value :%s\n", v)
27    }
28}

 1$go run main.go
 2Both Key and Value
 3key :a value: x
 4key :b value: y
 5
 6Only keys
 7key :a
 8key :b
 9
10Only values
11value :x
12value :y

1for index, character := range string {
2    //Do something with index and character
3}

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6    sample := "a£b"
 7
 8    //With index and value
 9    fmt.Println("Both Index and Value")
10    for i, letter := range sample {
11        fmt.Printf("Start Index: %d Value:%s\n", i, string(letter))
12    }
13
14    //Only value
15    fmt.Println("\nOnly value")
16    for _, letter := range sample {
17        fmt.Printf("Value:%s\n", string(letter))
18    }
19
20    //Only index
21    fmt.Println("\nOnly Index")
22    for i := range sample {
23        fmt.Printf("Start Index: %d\n", i)
24    }
25}

 1$ go run main.go
 2Both Index and Value
 3Start Index: 0 Value:a
 4Start Index: 1 Value:£
 5Start Index: 3 Value:b
 6
 7Only value
 8Value:a
 9Value:£
10Value:b
11
12Only Index
13Start Index: 0
14Start Index: 1
15Start Index: 3

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6	sum := 0
 7	for {
 8		sum++
 9		if sum == 10 {
10			break
11		}
12	}
13
14	fmt.Println(sum)
15	fmt.Println("now this line will execute")
16}

1$ go run main.go
210
3now this line will execute

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6    letters := []string{"a", "b", "c"}
 7
 8	for i := 1; i < 10; i++ {
 9        // define a lable with name 'second' for this loop
10        second:
11            for i := 2; i < 9; i++ {
12                for _, l := range letters {
13                    if l == "b" {
14                        // break the loop with second lable
15                        break second
16                    }
17                }
18            }
19	}
20}

 1package main
 2
 3import "fmt"
 4
 5func main() {
 6
 7	for i := 1; i < 10; i++ {
 8		if i%2 == 0 {
 9			continue
10		}
11		fmt.Println(i)
12	}
13}

1$ go run main.go
21
33
45
57
69