47 lines
776 B
Go
47 lines
776 B
Go
|
package main
|
||
|
|
|
||
|
|
import "bufio"
|
||
|
|
import "io"
|
||
|
|
import "log"
|
||
|
|
import "os"
|
||
|
|
import "strings"
|
||
|
|
|
||
|
|
func transform(in io.Reader, out io.Writer) {
|
||
|
|
bufw := bufio.NewWriter(out)
|
||
|
|
s := bufio.NewScanner(in)
|
||
|
|
for s.Scan() {
|
||
|
|
line := s.Text()
|
||
|
|
for i, c := range line {
|
||
|
|
if i == 0 {
|
||
|
|
bufw.WriteString(strings.ToLower(string(c)))
|
||
|
|
} else {
|
||
|
|
bufw.WriteString(string(c))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
bufw.WriteString("\n")
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
if len(os.Args) < 2 {
|
||
|
|
log.Fatalln("Usage upper-line <file>")
|
||
|
|
}
|
||
|
|
f, err := os.Open(os.Args[1])
|
||
|
|
if err != nil {
|
||
|
|
log.Fatalln("Error opening file", err)
|
||
|
|
}
|
||
|
|
defer f.Close()
|
||
|
|
|
||
|
|
var w io.Writer
|
||
|
|
if len(os.Args) >= 3 {
|
||
|
|
w, err = os.Create(os.Args[2])
|
||
|
|
if err != nil {
|
||
|
|
log.Fatalln("Error creating file", err)
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
w = os.Stdout
|
||
|
|
}
|
||
|
|
|
||
|
|
transform(f, w)
|
||
|
|
}
|