Re: File opening modes (r, w, a ...)
Lew Pitcher於 2018年2月23日星期五 UTC+8上午9時43分19秒寫道: > jf...@ms4.hinet.net wrote: > > > ast於 2018年2月22日星期四 UTC+8下午8時33分00秒寫道: > >> Hello > >> > >> I share a very valuable table I found on > >> StackOverflow about file opening modes > >> > >> If like me you always forget the details of > >> file opening mode, the following table provides > >> a good summary > >> > >>| r r+ w w+ a a+ > >> --|-- > >> read | + +++ > >> write | ++ ++ + > >> write after seek | ++ + > >> create| + ++ + > >> truncate | + + > >> position at start | + ++ + > >> position at end | + + > > > > What the "write after seek" means? > > It /should/ mean that programs are permitted to seek to a point in the file, > and then write from that point on. > > A write to a read mode ("r") file isn't permitted at all, > so neither is "write after seek" to a read mode file. > > A write to an append mode ("a" and "a+") file always write to the end of the > file, effectively negating any seek. > > HTH > > -- > Lew Pitcher > "In Skills, We Trust" > PGP public key available upon request Thank you for explanation. Mode 'r+', 'a' and 'a+' all can be seek and write, but only 'r+' was marked in the table. That's why I was confused. This row seems redundant to me:-) --Jach -- https://mail.python.org/mailman/listinfo/python-list
Re: File opening modes (r, w, a ...)
jf...@ms4.hinet.net wrote: > ast於 2018年2月22日星期四 UTC+8下午8時33分00秒寫道: >> Hello >> >> I share a very valuable table I found on >> StackOverflow about file opening modes >> >> If like me you always forget the details of >> file opening mode, the following table provides >> a good summary >> >>| r r+ w w+ a a+ >> --|-- >> read | + +++ >> write | ++ ++ + >> write after seek | ++ + >> create| + ++ + >> truncate | + + >> position at start | + ++ + >> position at end | + + > > What the "write after seek" means? It /should/ mean that programs are permitted to seek to a point in the file, and then write from that point on. A write to a read mode ("r") file isn't permitted at all, so neither is "write after seek" to a read mode file. A write to an append mode ("a" and "a+") file always write to the end of the file, effectively negating any seek. HTH -- Lew Pitcher "In Skills, We Trust" PGP public key available upon request -- https://mail.python.org/mailman/listinfo/python-list
Re: File opening modes (r, w, a ...)
ast於 2018年2月22日星期四 UTC+8下午8時33分00秒寫道: > Hello > > I share a very valuable table I found on > StackOverflow about file opening modes > > If like me you always forget the details of > file opening mode, the following table provides > a good summary > >| r r+ w w+ a a+ > --|-- > read | + +++ > write | ++ ++ + > write after seek | ++ + > create| + ++ + > truncate | + + > position at start | + ++ + > position at end | + + What the "write after seek" means? --Jach -- https://mail.python.org/mailman/listinfo/python-list
Re: File opening modes (r, w, a ...)
On Thu, 22 Feb 2018 13:32:45 +0100, ast wrote: > Hello > > I share a very valuable table I found on StackOverflow about file > opening modes > > If like me you always forget the details of file opening mode, the > following table provides a good summary Thanks! -- Steve -- https://mail.python.org/mailman/listinfo/python-list
File opening modes (r, w, a ...)
Hello I share a very valuable table I found on StackOverflow about file opening modes If like me you always forget the details of file opening mode, the following table provides a good summary | r r+ w w+ a a+ --|-- read | + +++ write | ++ ++ + write after seek | ++ + create| + ++ + truncate | + + position at start | + ++ + position at end | + + -- https://mail.python.org/mailman/listinfo/python-list