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jguo
jguo

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Learning Golang 103

#go #beginners

Functions

  • Multiple return values 
func nextInt(b []byte, i int) (int, int) { for ; i < len(b) && !isDigit(b[i]); i++ { } x := 0 for ; i < len(b) && isDigit(b[i]); i++ { x = x*10 + int(b[i]) - '0' } return x, i }
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  • Named result parameters The return or result "parameters" of a Go function can be given names and used as regular variables.When named, they are initialized to the zero values for their types when the function begins; if the function executes a return statement with no arguments, the current values of the result parameters are used as the returned values. 
func ReadFull(r Reader, buf []byte) (n int, err error) { for len(buf) > 0 && err == nil { var nr int nr, err = r.Read(buf) n += nr buf = buf[nr:] } return // default named result parameters. }
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  • Defer Go's defer statement schedules a function call (the deferred function) to be run immediately before the function executing the defer returns. 
// Contents returns the file's contents as a string. func Contents(filename string) (string, error) { f, err := os.Open(filename) if err != nil { return "", err } defer f.Close() // f.Close will run when we're finished. var result []byte buf := make([]byte, 100) for { n, err := f.Read(buf[0:]) result = append(result, buf[0:n]...) if err != nil { if err == io.EOF { break } return "", err // f will be closed if we return here. } } return string(result), nil // f will be closed if we return here. }
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