For #

for is Go’s only looping construct. Here are some basic types of for loops.

The most basic type, with a single condition.

i := 1
for i <= 3 {
	fmt.Println(i)
	i = i + 1
}
// Output:
// 1
// 2
// 3

A classic initial/condition/after for loop.

for j := 0; j < 3; j++ {
	fmt.Println(j)
}
// Output:
// 0
// 1
// 2

Another way of accomplishing the basic “do this N times” iteration is range over an integer.

for i := range 3 {
	fmt.Println("range", i)
}
// Output:
// range 0
// range 1
// range 2

for without a condition will loop repeatedly until you break out of the loop or return from the enclosing function.

for {
	fmt.Println("loop")
	break
}
// Output: loop

You can also continue to the next iteration of the loop.

for n := range 6 {
	if n%2 == 0 {
		continue
	}
	fmt.Println(n)
}
// Output:
// 1
// 3
// 5

We’ll see some other for forms later when we look at range statements, channels, and other data structures.