$Id: 192
$SOId: 20508
CSV is not a well-defined format. It doesn’t have a specification and there are many variants.
Package [encoding/csv](<https://golang.org/pkg/encoding/csv/>) supports most common CSV formats and allows tweaking reading and writing process.
After you create csv.Reader with csv.NewReader(), you can set the following fields to change the behavior.
Comma
Most CSV files use , to separate records but other characters are used too. If you have a file that uses ; as a separator you can configure a reader with r.Comma = ';'.
Comment
If you want to treat some CSV as comments and ignore them during reading, you can set a comment character.
For example if CSV file is:
# Comment
2013-02-08,15.07,AAL
you can ignore comment lines by setting r.Comment = '#'.
By default CSV reader doesn’t detect comments and will return an error trying to parse comment line.
FieldsPerRecord
Each line in a CSV file (a record) can have a different number of fields.
If you know that e.g. CSV file you’re parsing always has 5 fields in each record (line) then set r.FieldsPerRecord = 5. Read() will return an error if there’s a mismatch.
If you don’t know how many fields there are but know that it’s always the same number, use r.FieldsPerRecord = 0. This is a default so you don’t have to do it explicitly.
In that case csv.Reader will use the first line to detect number of fields and will return an error if subsequent records have a different number of fields.