While printing file names on my system using writef, I came across this file name: 311abc%20-%20tmb[1] (percent signs included) and received this error: 311abcError: std.format.

I'm guessing writef got tripped up because the % sign is used as part of a format string for writef.  I tried taking the file name and putting single, double and the wysiwyg identifier "r" in front of it and tried to print it with writef, but I still get the error.  Is there any way around this?  I wouldn't have been able to anticipate thie file name on my system, so, maybe writef is not a good candidate for what I'm doing?

This will reproduce the error:
# import std.stdio;
#
# void main()
# {
#     writef("311abc%20-%20tmb[1]");
# }

-Kramer

Kramer wrote:

> I'm guessing writef got tripped up because the % sign is used as part of a
> format string for writef.  I tried taking the file name and putting single,
> double and the wysiwyg identifier "r" in front of it and tried to print it with
> writef, but I still get the error.  Is there any way around this?  I wouldn't
> have been able to anticipate thie file name on my system, so, maybe writef is
> not a good candidate for what I'm doing?

The first argument to writef is *not* a string, but a format specifier.

Thus, you need to use this instead: writefln("%s","311abc%20-%20tmb[1]")

Works the same way as with printf (in C).

--anders

In article <cth792$mc8$1@digitaldaemon.com>, Kramer says...
>
>Is there any way around this?

>This will reproduce the error:
># import std.stdio;
>#
># void main()
># {
>#     writef("311abc%20-%20tmb[1]");
># }

Try this instead:

> writefln("%s","311abc%20-%20tmb[1]");

- EricAnderton at yahoo

D'oh!

Thanks!

-Kramer

In article <cth8jr$ni2$1@digitaldaemon.com>, =?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= says...
>
>Kramer wrote:
>
>> I'm guessing writef got tripped up because the % sign is used as part of a format string for writef.  I tried taking the file name and putting single, double and the wysiwyg identifier "r" in front of it and tried to print it with writef, but I still get the error.  Is there any way around this?  I wouldn't have been able to anticipate thie file name on my system, so, maybe writef is not a good candidate for what I'm doing?
>
>The first argument to writef is *not* a string, but a format specifier.
>
>Thus, you need to use this instead: writefln("%s","311abc%20-%20tmb[1]")
>
>Works the same way as with printf (in C).
>
>--anders

In article <cth8jr$ni2$1@digitaldaemon.com>, =?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= says...
>
>The first argument to writef is *not* a string, but a format specifier.
>
>Thus, you need to use this instead: writefln("%s","311abc%20-%20tmb[1]")
>
>Works the same way as with printf (in C).
>
>--anders

This seems to be a common source of mistakes, and maybe something should be done
about it. We could for example have two additional functions called
write()/writeln(), which do not accept format strings, but otherwise works as
writef() and writefln()?

Nick

Nick wrote:

>>The first argument to writef is *not* a string, but a format specifier.
>>Thus, you need to use this instead: writefln("%s","311abc%20-%20tmb[1]")
>>
>>Works the same way as with printf (in C).
> 
> This seems to be a common source of mistakes, and maybe something should be done
> about it. We could for example have two additional functions called
> write()/writeln(), which do not accept format strings, but otherwise works as
> writef() and writefln()?

Yes, seems like a good idea. In C, there is "puts" which does writeln.
Such a "stupid" function should also be faster than the full writef ?

I believe OutputStream has a bunch of overloaded "write()" functions,
but there are no such alternatives in std.stdio as far as I can tell.


I'm also wondering how you output an ubyte[] full of 8-bit characters ?
Using "%s" just gives the "invalid UTF-8 sequence" error with writef...

Input and output to non-Unicode/UTF is something of a pain, in general.
But I suppose I can do it on the stdin/stdout streams instead of stdio.

--anders

Nick wrote:

> This seems to be a common source of mistakes, and maybe something should be done
> about it. We could for example have two additional functions called
> write()/writeln(), which do not accept format strings, but otherwise works as
> writef() and writefln()?

Here's one trivial implementation of those:

> import std.stdio;
> import std.stream;
> 
> void write(char[] str)
> {
>      std.stream.stdout.writeString(str);
> }
> 
> void writeln(char[] str)
> {
>      std.stream.stdout.writeLine(str);
> }
> 
> void main()
> {
>    writef("*** Hall\u00e5, ");
>    writefln("V\u00e4rlden! ***");
>    write("%%% Hall\u00e5, ");
>    writeln("V\u00e4rlden! %%%");
> }

It doesn't work for wchar[] or dchar[], though ?
(You can't overload them, because of the literals)

--anders

In article <ctlfea$nh7$1@digitaldaemon.com>, =?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= says...
>
>Nick wrote:
>
>> This seems to be a common source of mistakes, and maybe something should be done
>> about it. We could for example have two additional functions called
>> write()/writeln(), which do not accept format strings, but otherwise works as
>> writef() and writefln()?
>
>Here's one trivial implementation of those:
>
> [snip]

I was thinking more in the line of functions which can print anything, not just strings. So writing eg.

# int i, j;
# char[] str;
# ...
# writeln(i, str, j, " hello");

would do exactly the same as

# writefln(i, str, j, " hello");

except it would be safe if str contains any '%'-characters.

Nick

Nick schrieb:
> I was thinking more in the line of functions which can print anything, not just
> strings. So writing eg.
> 
> # int i, j;
> # char[] str;
> # ...
> # writeln(i, str, j, " hello");
> 
> would do exactly the same as
> 
> # writefln(i, str, j, " hello");
> 
> except it would be safe if str contains any '%'-characters.

This would mean adding another way to accomplish exactly the same as writef does, which in general is a bad idea.

It isn't easier to explain to a noob the difference between write/writef than between writef(str) and writef("%s", str).

-Sebastian

In article <ctlqte$17hd$1@digitaldaemon.com>, Sebastian Beschke says...
>
>This would mean adding another way to accomplish exactly the same as writef does, which in general is a bad idea.

Why is that a bad idea? (I'm not contesting that it is, just asking.)

>It isn't easier to explain to a noob the difference between write/writef than between writef(str) and writef("%s", str).

Sure it is. You say

"Use write/writeln for output, eg.

writeln(a,b,c).

If you need specially formatted output, use the writef/writefln, eg.

writefln("%-20s %5d", s, i);"

But saying that you can't write eg.

int i;
cdouble d;
MyNumberClass m;
..
writefln(i, d, m);

because m.toString might in theory return a '%' seems pretty counter-intuitive too me.

Nick