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go/doc/progs/cat.go
Russ Cox 60ce95d7a1 code changes for array conversion.
as a reminder, the old conversion
was that you could write

	var arr [10]byte;
	var slice []byte;
	slice = arr;

but now you have to write

	slice = &arr;

the change eliminates an implicit &, so that
the only implicit &s left are in the . operator
and in string(arr).

also, removed utf8.EncodeRuneToString
in favor of string(rune).

R=r
DELTA=83  (1 added, 23 deleted, 59 changed)
OCL=27531
CL=27534
2009-04-15 20:27:45 -07:00

47 lines
983 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 (
"file";
"flag";
"fmt";
"os";
)
func cat(f *file.File) {
const NBUF = 512;
var buf [NBUF]byte;
for {
switch nr, er := f.Read(&buf); true {
case nr < 0:
fmt.Fprintf(os.Stderr, "error reading from %s: %s\n", f.String(), er.String());
sys.Exit(1);
case nr == 0: // EOF
return;
case nr > 0:
if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr {
fmt.Fprintf(os.Stderr, "error writing from %s: %s\n", f.String(), ew.String());
}
}
}
}
func main() {
flag.Parse(); // Scans the arg list and sets up flags
if flag.NArg() == 0 {
cat(file.Stdin);
}
for i := 0; i < flag.NArg(); i++ {
f, err := file.Open(flag.Arg(i), 0, 0);
if f == nil {
fmt.Fprintf(os.Stderr, "can't open %s: error %s\n", flag.Arg(i), err);
sys.Exit(1);
}
cat(f);
f.Close();
}
}