35 lines
636 B
Go
35 lines
636 B
Go
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bufio"
|
||
|
|
"fmt"
|
||
|
|
"os"
|
||
|
|
"strconv"
|
||
|
|
"strings"
|
||
|
|
)
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
if len(os.Args) < 2 {
|
||
|
|
fmt.Fprintf(os.Stderr, "usage: %s <field-number>", os.Args[0])
|
||
|
|
os.Exit(1)
|
||
|
|
}
|
||
|
|
|
||
|
|
fieldNum, err := strconv.Atoi(os.Args[1])
|
||
|
|
if err != nil || fieldNum < 1 {
|
||
|
|
fmt.Fprintln(os.Stderr, "invalid field number:", os.Args[1])
|
||
|
|
os.Exit(1)
|
||
|
|
}
|
||
|
|
|
||
|
|
scanner := bufio.NewScanner(os.Stdin)
|
||
|
|
for scanner.Scan() {
|
||
|
|
line := scanner.Text()
|
||
|
|
fields := strings.Fields(line)
|
||
|
|
if len(fields) >= fieldNum {
|
||
|
|
fmt.Println(fields[fieldNum-1])
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if err := scanner.Err(); err != nil {
|
||
|
|
fmt.Fprintln(os.Stderr, "error reading input:", err)
|
||
|
|
}
|
||
|
|
}
|