Go Scan, Scanf, Scanln, ReadString

In go, 4 methods are commonly used for read from stdin.
Scan, Scanf, Scanln, ReadString.

They are different in that:

• Scan read space separated values into successive arguments.
• Scanln also read space separated values into successive arguments, but terminate until a new line is reached.
• Scanf does the same, but is uses the its first parameter as format string to read the values in the variables.
• ReadString read string until some character is reached.

Read from stdin in go is rather different from that of python. Following issues need to be taken care of.

• Use Scan* in inner loop is a bad idea. The internals of scan* do some state bookkeeping on every call.
• ReadString contain tailling \n. If you want the standard python input() behavior. The following may be useful for you.

import (
	"strings"
	"bufio"
	"os"
)

var stdin *bufio.Reader
func init() {
	stdin = bufio.NewReader(os.Stdin)
}

func input() string {
	s, _ := stdin.ReadString('\n')
	return strings.TrimRight(s, "\n")
}

• Atoi fail if string has tailling \n

A better way to scan line by line is

scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
	fmt.Println(scanner.Text())
}