• WhatMeWorry (9/9) Oct 13 2022 I was a little (nicely) surprised that I could use double quotes,
• =?UTF-8?Q?Ali_=c3=87ehreli?= (33/36) Oct 13 2022 That one is a single character and very lightweigth because it's just an...
• rassoc (18/19) Oct 13 2022 You won't see a difference for this specific example since the split fun...

WhatMeWorry <kheaser gmail.com> writes:

I was a little (nicely) surprised that I could use double quotes, 
single quotes, or back ticks in the following line of code.

return s.split(";");  // double quotes
or
return s.split(';');  // single quotes
or
return s.split(`;`);  // back ticks

Does D provide any guidance as to what is preferred or are they 
identical for all intents and purposes?

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

Changing the order of lines...

On 10/13/22 16:43, WhatMeWorry wrote:

 return s.split(';');  // single quotes

That one is a single character and very lightweigth because it's just an 
integral value. You can't put more than one character within single quotes:

  ';x' // ERROR

 return s.split(";");  // double quotes

That one is a string, which is the equivalent of the following "fat 
pointer":

struct Array_ {
   size_t length;
   char * ptr;
}

For that reason, it can be seen as a little bit more costly. 'length' 
happens to be 1 but you can use multiple characters in a string:

   ";x" // works

(Aside: There is also a '\0' character sitting next to the ';' in memory 
so that the literal can be passed to C functions as-is.)

Double-quoted strings have the property of escaping. For example, "\n" 
is not 2 characters but is "the newline character".

 return s.split(`;`);  // back ticks

They are strings as well but they don't do escaping: `\n` happens to be 
2 characters.

There is also strings that start with q{ and end with }:

   auto myString = q{
       hello
       world
   };

And then there is delimited strings that use any delimiter you choose:

     auto myString = q"MY_DELIMITER
hello
world
MY_DELIMITER";

Some information here:

   http://ddili.org/ders/d.en/literals.html#ix_literals.string%20literal

Ali

rassoc <rassoc posteo.de> writes:

On 10/14/22 01:43, WhatMeWorry via Digitalmars-d-learn wrote:
 Does D provide any guidance as to what is preferred or are they identical for
all intents and purposes?

You won't see a difference for this specific example since the split function
supports character, string and even range separators. So, use what works best
for your use case.

But here's the difference between them:

Single quotes are for singular characters, 'hello' won't compile while ';' and
'\n' (escaped newline) will.

Double quotes are string literals, i.e. array of characters, which also allow
escape sequences like "\r\n".

Back ticks, as well as r"...", are raw or wysiwyg ("what you see is what you
get") strings, they do not support escape sequences. They are super useful for
regex.

import std;
void main() {
     writeln("ab\ncd");  // \n is recognized as a newline character
     writeln(`ab\ncd`);  // `...` and r"..." are equivalent
     writeln(r"ab\ncd");
}

will print:

ab
cd
ab\ncd
ab\ncd

More info here, if you are interested:
https://dlang.org/spec/lex.html#string_literals