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digitalmars.D.learn - How to make a formatted string ?

reply Gabriel Laskar <gabriel lse.epita.fr> writes:
Hi,

I am searching how to do a formatted string like with sprintf()

I have found std.format.formattedWrite() but when I try :

Appender!(string) msg;
formattedWrite(msg, "toto: %0", 42);
writeln(msg);

It fails with :
core.exception.RangeError �(1582): Range violation

I have also found std.string.format, but it seems to fail also.
Mar 17 2010
next sibling parent "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
Gabriel Laskar wrote:
 Hi,
 
 I am searching how to do a formatted string like with sprintf()
 
 I have found std.format.formattedWrite() but when I try :
 
 Appender!(string) msg;
 formattedWrite(msg, "toto: %0", 42);
 writeln(msg);
 
 It fails with :
 core.exception.RangeError �(1582): Range violation
 
 I have also found std.string.format, but it seems to fail also.

There are two problems here: 1. Your format specification is wrong. %0 is not a valid specifier. 2. msg isn't a string, it's an Appender. Extract its contents with Appender.data instead. Here's one example of how to do it: Appender!string msg; formattedWrite(msg, "toto: %s", 42); write(msg.data); If you meant to use positional parameters, then the first parameter is number 1, not 0, and you also need a format specifier. The syntax is then formattedWrite(msg, "toto: %1$s", 42); (This is the POSIX syntax, check out http://opengroup.org/onlinepubs/009695399/functions/printf.html for the full specification.) -Lars
Mar 17 2010
prev sibling next sibling parent "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
Gabriel Laskar wrote:
 I have also found std.string.format, but it seems to fail also.

I forgot to mention: std.string.format() works if you use a correct format specification. string msg = format("hello: %s", 42); It doesn't seem to support positional parameters, though. -Lars
Mar 17 2010
prev sibling parent reply Gabriel Laskar <gabriel lse.epita.fr> writes:
On 03/17/2010 12:59 PM, Gabriel Laskar wrote:
 Hi,

 I am searching how to do a formatted string like with sprintf()

 I have found std.format.formattedWrite() but when I try :

 Appender!(string) msg;
 formattedWrite(msg, "toto: %0", 42);
 writeln(msg);

 It fails with :
 core.exception.RangeError �(1582): Range violation

 I have also found std.string.format, but it seems to fail also.

Oops, I'm stupid, It is not %0, but %s... std.string.format is good. Now I need to pass an array of char[] instead of va_args, I have found a work around, but it seems bad : string formatArray(char[][] args) { switch (args.length) { case 1: return format(args[0]); case 2: return format(args[0], args[1]); // ... } } If someone have something better... Cheers. __ Gabriel Laskar <gabriel lse.epita.fr0>
Mar 17 2010
parent reply "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
Gabriel Laskar wrote:
 On 03/17/2010 12:59 PM, Gabriel Laskar wrote:
 Hi,

 I am searching how to do a formatted string like with sprintf()

 I have found std.format.formattedWrite() but when I try :

 Appender!(string) msg;
 formattedWrite(msg, "toto: %0", 42);
 writeln(msg);

 It fails with :
 core.exception.RangeError �(1582): Range violation

 I have also found std.string.format, but it seems to fail also.

Oops, I'm stupid, It is not %0, but %s... std.string.format is good. Now I need to pass an array of char[] instead of va_args, I have found a work around, but it seems bad : string formatArray(char[][] args) { switch (args.length) { case 1: return format(args[0]); case 2: return format(args[0], args[1]); // ... } } If someone have something better...

It depends on what you are trying to do. char[][] a = ["hello".dup, "world".dup]; string fmt = format(a); // fmt is now "[hello,world]" char[][] a = ["hello %s %s world".dup, "foo".dup, "bar".dup]; string fmt = format(a[0], a[1 .. $]); // fmt is now "hello foo bar world" -Lars
Mar 17 2010
next sibling parent Gabriel Laskar <gabriel lse.epita.fr> writes:
On 03/17/2010 02:58 PM, Lars T. Kyllingstad wrote:
 char[][] a = ["hello %s %s world".dup, "foo".dup, "bar".dup];
 string fmt = format(a[0], a[1 .. $]);
 // fmt is now "hello foo bar world"

thats perfect, thanks __ Gabriel Laskar <gabriel lse.epita.fr0>
Mar 17 2010
prev sibling parent reply Gabriel Laskar <gabriel lse.epita.fr> writes:
On 03/17/2010 02:58 PM, Lars T. Kyllingstad wrote:
 char[][] a = ["hello %s %s world".dup, "foo".dup, "bar".dup];
 string fmt = format(a[0], a[1 .. $]);
 // fmt is now "hello foo bar world"

I have another problem : 1 import std.stdio; 2 import std.string; 3 4 int main() 5 { 6 char[][] a = ["expected %s but found %s".dup, "42".dup, "32".dup]; 7 8 writeln(format(a[0], a[1 .. $])); 9 10 return 0; 11 } Does not work : $ dmd-phobos -run format.d std.format.FormatError: std.format but : 1 import std.stdio; 2 import std.string; 3 4 int main() 5 { 6 char[][] a = ["expected %s".dup, "42".dup]; 7 8 writeln(format(a[0], a[1 .. $])); 9 10 return 0; 11 } does not seems to work either : $ dmd-phobos -run format.d expected [42] Did I miss something ? -- Gabriel Laskar <gabriel lse.epita.fr>
Mar 17 2010
parent Ellery Newcomer <ellery-newcomer utulsa.edu> writes:
On 03/17/2010 11:21 AM, Gabriel Laskar wrote:
 I have another problem :

 1 import std.stdio;
 2 import std.string;
 3
 4 int main()
 5 {
 6 char[][] a = ["expected %s but found %s".dup, "42".dup, "32".dup];
 7
 8 writeln(format(a[0], a[1 .. $]));
 9
 10 return 0;
 11 }

 Does not work :
 $ dmd-phobos -run format.d
 std.format.FormatError: std.format

format wants to put the entire a[1 .. $] in the first %s. There isn't anything left over for the second %s
 but :

 1 import std.stdio;
 2 import std.string;
 3
 4 int main()
 5 {
 6 char[][] a = ["expected %s".dup, "42".dup];
 7
 8 writeln(format(a[0], a[1 .. $]));
 9
 10 return 0;
 11 }

 does not seems to work either :
 $ dmd-phobos -run format.d
 expected [42]

 Did I miss something ?

ditto. To get what you want, you're probably going to have to mess around with std.format.doFormat and implement your own format function.
Mar 17 2010