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selectColumn.go
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/
selectColumn.go
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package main
import (
"bufio"
"fmt"
"io"
"os"
"strconv"
"strings"
)
func main() {
arguments := os.Args
if len(arguments) < 2 {
fmt.Printf("usage: selectColumn column <file1> [<file2> [... <fileN]]\n")
os.Exit(1)
}
temp, err := strconv.Atoi(arguments[1])
if err != nil {
fmt.Println("Column value is not an integer:", temp)
return
}
column := temp
if column < 0 {
fmt.Println("Invalid Column number!")
os.Exit(1)
}
for _, filename := range arguments[2:] {
fmt.Println("\t\t", filename)
f, err := os.Open(filename)
if err != nil {
fmt.Printf("error opening file %s\n", err)
continue
}
defer f.Close()
r := bufio.NewReader(f)
for {
line, err := r.ReadString('\n')
if err == io.EOF {
break
} else if err != nil {
fmt.Printf("error reading file %s", err)
}
data := strings.Fields(line)
if len(data) >= column {
fmt.Println((data[column-1]))
}
}
}
}