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
diff --git a/doc/go_tutorial.html b/doc/go_tutorial.html
index 4d9c63e..c87254e 100644
--- a/doc/go_tutorial.html
+++ b/doc/go_tutorial.html
@@ -741,26 +741,27 @@
24 case nr > 0:
25 if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr {
26 fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", f.String(), ew.String())
-27 }
-28 }
-29 }
-30 }
+27 os.Exit(1)
+28 }
+29 }
+30 }
+31 }
<p>
-32 func main() {
-33 flag.Parse() // Scans the arg list and sets up flags
-34 if flag.NArg() == 0 {
-35 cat(file.Stdin)
-36 }
-37 for i := 0; i < flag.NArg(); i++ {
-38 f, err := file.Open(flag.Arg(i))
-39 if f == nil {
-40 fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err)
-41 os.Exit(1)
-42 }
-43 cat(f)
-44 f.Close()
-45 }
-46 }
+33 func main() {
+34 flag.Parse() // Scans the arg list and sets up flags
+35 if flag.NArg() == 0 {
+36 cat(file.Stdin)
+37 }
+38 for i := 0; i < flag.NArg(); i++ {
+39 f, err := file.Open(flag.Arg(i))
+40 if f == nil {
+41 fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err)
+42 os.Exit(1)
+43 }
+44 cat(f)
+45 f.Close()
+46 }
+47 }
</pre>
<p>
By now this should be easy to follow, but the <code>switch</code> statement introduces some
@@ -858,10 +859,11 @@
67 nw, ew := file.Stdout.Write(buf[0:nr])
68 if nw != nr {
69 fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", r.String(), ew.String())
-70 }
-71 }
-72 }
-73 }
+70 os.Exit(1)
+71 }
+72 }
+73 }
+74 }
</pre>
<p>
(We could also do the wrapping in <code>main</code> and leave <code>cat()</code> mostly alone, except
@@ -1238,7 +1240,7 @@
28 func main() {
29 ch := make(chan int) // Create a new channel.
30 go generate(ch) // Start generate() as a goroutine.
-31 for {
+31 for i := 0; i < 100; i++ { // Print the first hundred primes.
32 prime := <-ch
33 fmt.Println(prime)
34 ch1 := make(chan int)
@@ -1318,7 +1320,7 @@
<pre> <!-- progs/sieve1.go /func.main/ /^}/ -->
46 func main() {
47 primes := sieve()
-48 for {
+48 for i := 0; i < 100; i++ { // Print the first hundred primes.
49 fmt.Println(<-primes)
50 }
51 }
diff --git a/doc/progs/sieve.go b/doc/progs/sieve.go
index fb649e0..c7c3e78 100644
--- a/doc/progs/sieve.go
+++ b/doc/progs/sieve.go
@@ -28,7 +28,7 @@
func main() {
ch := make(chan int) // Create a new channel.
go generate(ch) // Start generate() as a goroutine.
- for {
+ for i := 0; i < 100; i++ { // Print the first hundred primes.
prime := <-ch
fmt.Println(prime)
ch1 := make(chan int)
diff --git a/doc/progs/sieve1.go b/doc/progs/sieve1.go
index 71468d0..e785e20 100644
--- a/doc/progs/sieve1.go
+++ b/doc/progs/sieve1.go
@@ -45,7 +45,7 @@
func main() {
primes := sieve()
- for {
+ for i := 0; i < 100; i++ { // Print the first hundred primes.
fmt.Println(<-primes)
}
}
