| Writing files in Go follows similar patterns to the ones we saw earlier for reading. | ||
package main |
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import ( |
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"bufio" |
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"fmt" |
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"io/ioutil" |
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"os" |
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) |
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func check(e error) { |
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if e != nil { |
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panic(e) |
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} |
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} |
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func main() { |
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| To start, here's how to dump a string (or just bytes) into a file. | d1 := []byte("hello\ngo\n") |
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err := ioutil.WriteFile("/tmp/dat1", d1, 0644) |
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check(err) |
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| For more granular writes, open a file for writing. | f, err := os.Create("/tmp/dat2") |
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check(err) |
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| It's idiomatic to defer a `Close` immediately after opening a file. | defer f.Close() |
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| You can `Write` byte slices as you'd expect. | d2 := []byte{115, 111, 109, 101, 10} |
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n2, err := f.Write(d2) |
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check(err) |
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fmt.Printf("wrote %d bytes\n", n2) |
wrote 5 bytes |
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| A `WriteString` is also available. | n3, err := f.WriteString("writes\n") |
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check(err) |
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fmt.Printf("wrote %d bytes\n", n3) |
wrote 7 bytes |
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| Issue a `Sync` to flush writes to stable storage. | f.Sync() |
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| `bufio` provides buffered writers in addition to the buffered readers we saw earlier. | w := bufio.NewWriter(f) |
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n4, err := w.WriteString("buffered\n") |
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check(err) |
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fmt.Printf("wrote %d bytes\n", n4) |
wrote 9 bytes |
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| Use `Flush` to ensure all buffered operations have been applied to the underlying writer. | w.Flush() |
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} |