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go/doc/progs/sieve.go
Rob Pike 2ccd20a646 tutorial: replace the forever loops with finite counts in sieve programs.
Fixes #1742.
I hope.

Also this picks up an update to go_tutorial.html that should already have happened.

R=brainman, rsc, peterGo
CC=golang-dev
https://golang.org/cl/4452050
2011-04-27 09:59:27 -07:00

39 lines
959 B
Go

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "fmt"
// Send the sequence 2, 3, 4, ... to channel 'ch'.
func generate(ch chan int) {
for i := 2; ; i++ {
ch <- i // Send 'i' to channel 'ch'.
}
}
// Copy the values from channel 'in' to channel 'out',
// removing those divisible by 'prime'.
func filter(in, out chan int, prime int) {
for {
i := <-in // Receive value of new variable 'i' from 'in'.
if i % prime != 0 {
out <- i // Send 'i' to channel 'out'.
}
}
}
// The prime sieve: Daisy-chain filter processes together.
func main() {
ch := make(chan int) // Create a new channel.
go generate(ch) // Start generate() as a goroutine.
for i := 0; i < 100; i++ { // Print the first hundred primes.
prime := <-ch
fmt.Println(prime)
ch1 := make(chan int)
go filter(ch, ch1, prime)
ch = ch1
}
}