Iterate over multiline string in Go

Question

In Python I can iterate over a multiline string.

x = """\
this is
my multiline
string!"""

for line in x.splitlines():
    print(line)

Can Go do the same?

Answer 1

You can use bufio.Scanner in Go which iterates over lines from an io.Reader. The following example creates a reader from the given multiline string and passes it to the scanner factory function. Each invocation of scanner.Scan() splits the reader on the next line and buffers the line. If there is no more lines it returns false. Calling scanner.Text() returns the buffered split.

var x string = `this is
my multiline
string`

scanner := bufio.NewScanner(strings.NewReader(x))
for scanner.Scan() {
    fmt.Println(scanner.Text())
}

In the example, the for loop will continue until Scan() returns false at the end of the multiline string. In each loop we print the line returned by the scan.

https://play.golang.org/p/U9_B4TsH6M

Answer 2

If you want to iterate over a multiline string literal as shown in the question, then use this code:

for _, line := range strings.Split(strings.TrimSuffix(x, "\n"), "\n") {
    fmt.Println(line)
}

Run the code on the playground

If you want to iterate over data read from a file, use bufio.Scanner. The documentation has an example showing how to iterate over lines:

scanner := bufio.NewScanner(f) // f is the *os.File
for scanner.Scan() {
    fmt.Println(scanner.Text()) // Println will add back the final '\n'
}
if err := scanner.Err(); err != nil {
   // handle error
}

Answer 3

I think using bufio is the best option, but if you do need to just split a string, I think TrimRight is better than TrimSuffix, as it could cover any combination of repeated trailing newlines or carriage returns:

package main
import "strings"

func main() {
   x := `this is
my multiline
string!
`
   for _, line := range strings.Split(strings.TrimRight(x, "\n"), "\n") {
      println(line)
   }
}

https://golang.org/pkg/strings#TrimRight