4回目課題実装 #23
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4回目課題実装 #23
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mf-sakura
reviewed
Apr 6, 2020
| @@ -6,6 +6,7 @@ func main() { | |||
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| numbers := make([]*int, 0, 3) | |||
| for i := 0; i < 3; i++ { | |||
| i := i | |||
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| keys := make([]int, 0, len(studnetIDMap)) | ||
| for k := range studnetIDMap { | ||
| keys = append(keys, k) | ||
| } | ||
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| for k, v := range studnetIDMap { | ||
| sort.Ints(keys) | ||
| for _, k := range keys { | ||
| // fmt.Printfでフォーマットに従った文字列を標準出力に出せる | ||
| fmt.Printf("Name of StudentID:%d is %s\n", k, studnetIDMap[k]) | ||
| } | ||
| } | ||
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| fmt.Printf("the address of n is %v\n", &n) | ||
| return n + 1 | ||
| } | ||
| func incrementWithPointer(n *int) { | ||
| fmt.Printf("the address of n is %v\n", &n) |
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main関数側のaddressもprintする必要がありました。
| @@ -24,7 +24,7 @@ func CatFile(path string) (err error) { | |||
| fmt.Println("Error Handling in defer called.") | |||
| } | |||
| // fileはCloseする必要がある。 | |||
| file.Close() | |||
| err = file.Close() | |||
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これだと他のエラーを上書きしてしまうので、
以下の様にnilで無ければ上書きする実装の方が良いと思います。
if closeErr := file.Close(); closeErr != nil {
err = closeErr
}
これでもfile.Close()がエラーを出した時は元のエラーを上書きしてしまうので、本当は2つのエラーを結合する処理が必要になります。ややこしいので講義では触れていません。
github.com/pkg/errorsを使った実装例
err = errors.Wrap(err, closeErr.Error())
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