Package fixedwidth provides encoding and decoding for fixed-width formatted Data.
go get github.com/ianlopshire/go-fixedwidth
Position within a line is controlled via struct tags.
The tags should be formatted as fixed:"{startPos},{endPos}" where startPos and endPos are both positive integers greater than 0.
Positions start at 1. The interval is inclusive. Fields without tags are ignored.
// define some data to encode
people := []struct {
ID int `fixed:"1,5"`
FirstName string `fixed:"6,15"`
LastName string `fixed:"16,25"`
Grade float64 `fixed:"26,30"`
}{
{1, "Ian", "Lopshire", 99.5},
}
data, err := fixedwidth.Marshal(people)
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s", data)
// Output:
// 1 Ian Lopshire 99.50// define the format
var people []struct {
ID int `fixed:"1,5"`
FirstName string `fixed:"6,15"`
LastName string `fixed:"16,25"`
Grade float64 `fixed:"26,30"`
}
// define some fixed-with data to parse
data := []byte("" +
"1 Ian Lopshire 99.50" + "\n" +
"2 John Doe 89.50" + "\n" +
"3 Jane Doe 79.50" + "\n")
err := fixedwidth.Unmarshal(data, &people)
if err != nil {
log.Fatal(err)
}
fmt.Printf("%+v\n", people[0])
fmt.Printf("%+v\n", people[1])
fmt.Printf("%+v\n", people[2])
// Output:
//{ID:1 FirstName:Ian LastName:Lopshire Grade:99.5}
//{ID:2 FirstName:John LastName:Doe Grade:89.5}
//{ID:3 FirstName:Jane LastName:Doe Grade:79.5}MIT