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digitalmars.D.learn - Load entire file, as a char array.

reply Chris Katko <ckatko gmail.com> writes:
This should be simple? All I want to do is load an entire file, 
and access individual bytes. The entire thing. I don't want to 
have know the file size before hand, or "guess" and have a 
"maximum size" buffer.

So far, all google searches for "dlang binary file read" end up 
not working for me.

Thank you.
Sep 02 2018
parent reply Neia Neutuladh <neia ikeran.org> writes:
On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko wrote:

 This should be simple? All I want to do is load an entire file, 
 and access individual bytes. The entire thing. I don't want to 
 have know the file size before hand, or "guess" and have a 
 "maximum size" buffer.

 So far, all google searches for "dlang binary file read" end up 
 not working for me.

 Thank you.


http://dpldocs.info/experimental-docs/std.file.read.1.html

import std.file : read;
auto bytes = read("filename");

This gives you a void[], which you can cast to ubyte[] or char[] 
or whatever you need.
Sep 02 2018
next sibling parent Chris Katko <ckatko gmail.com> writes:
On Monday, 3 September 2018 at 03:19:39 UTC, Neia Neutuladh wrote:

 On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko wrote:

 This should be simple? All I want to do is load an entire 
 file, and access individual bytes. The entire thing. I don't 
 want to have know the file size before hand, or "guess" and 
 have a "maximum size" buffer.

 So far, all google searches for "dlang binary file read" end 
 up not working for me.

 Thank you.


 http://dpldocs.info/experimental-docs/std.file.read.1.html

 import std.file : read;
 auto bytes = read("filename");

 This gives you a void[], which you can cast to ubyte[] or 
 char[] or whatever you need.


That works great! I thought all file i/o had to through the File 
class.
Sep 02 2018
prev sibling parent reply bauss <jj_1337 live.dk> writes:
On Monday, 3 September 2018 at 03:19:39 UTC, Neia Neutuladh wrote:

 On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko wrote:

 This should be simple? All I want to do is load an entire 
 file, and access individual bytes. The entire thing. I don't 
 want to have know the file size before hand, or "guess" and 
 have a "maximum size" buffer.

 So far, all google searches for "dlang binary file read" end 
 up not working for me.

 Thank you.


 http://dpldocs.info/experimental-docs/std.file.read.1.html

 import std.file : read;
 auto bytes = read("filename");

 This gives you a void[], which you can cast to ubyte[] or 
 char[] or whatever you need.


Or he could do readText() which returns a string, which in turn 
will give a proper char array when casted.
Sep 02 2018
parent reply bauss <jj_1337 live.dk> writes:
On Monday, 3 September 2018 at 06:25:23 UTC, bauss wrote:

 On Monday, 3 September 2018 at 03:19:39 UTC, Neia Neutuladh 
 wrote:

 On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko wrote:

 This should be simple? All I want to do is load an entire 
 file, and access individual bytes. The entire thing. I don't 
 want to have know the file size before hand, or "guess" and 
 have a "maximum size" buffer.

 So far, all google searches for "dlang binary file read" end 
 up not working for me.

 Thank you.


 http://dpldocs.info/experimental-docs/std.file.read.1.html

 import std.file : read;
 auto bytes = read("filename");

 This gives you a void[], which you can cast to ubyte[] or 
 char[] or whatever you need.


 Or he could do readText() which returns a string, which in turn 
 will give a proper char array when casted.


Actually ignore the casting thing, looking at readText it takes a 
template parameter.

So:

char[] a = readText!(char[])("filename");
Sep 02 2018
parent reply Chris Katko <ckatko gmail.com> writes:
On Monday, 3 September 2018 at 06:28:38 UTC, bauss wrote:

 On Monday, 3 September 2018 at 06:25:23 UTC, bauss wrote:

 On Monday, 3 September 2018 at 03:19:39 UTC, Neia Neutuladh 
 wrote:

 On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko 
 wrote:

 This should be simple? All I want to do is load an entire 
 file, and access individual bytes. The entire thing. I don't 
 want to have know the file size before hand, or "guess" and 
 have a "maximum size" buffer.

 So far, all google searches for "dlang binary file read" end 
 up not working for me.

 Thank you.


 http://dpldocs.info/experimental-docs/std.file.read.1.html

 import std.file : read;
 auto bytes = read("filename");

 This gives you a void[], which you can cast to ubyte[] or 
 char[] or whatever you need.


 Or he could do readText() which returns a string, which in 
 turn will give a proper char array when casted.


 Actually ignore the casting thing, looking at readText it takes 
 a template parameter.

 So:

 char[] a = readText!(char[])("filename");


Thanks, that works!

But... I'm so confused by D's fifty different string types.

I can run .strip() on a char[]. But I can't run 
.replace('\n','?') ?

So then I convert char[] to a temporary string and run replace on 
that.

but then writefln("%s") doesn't accept strings! Only char[].

   char []t = cast(char[])(c[i-15 .. i+1]).strip();
   string s = text(t); //s.replace('\n','?')
   writefln(" - [%s]", s); // fail

main.d(89): Error: template std.array.replace cannot deduce 
function from argument types !()(char[], char, char), candidates 
are:
/usr/include/dmd/phobos/std/array.d(2122):        
std.array.replace(E, R1, R2)(E[] subject, R1 from, R2 to) if 
(isDynamicArray!(E[]) && isForwardRange!R1 && isForwardRange!R2 
&& (hasLength!R2 || isSomeString!R2))
/usr/include/dmd/phobos/std/array.d(2255):        
std.array.replace(T, Range)(T[] subject, size_t from, size_t to, 
Range stuff) if (isInputRange!Range && (is(ElementType!Range : T) 
|| isSomeString!(T[]) && is(ElementType!Range : dchar)))


What's going on here?
Sep 03 2018
next sibling parent Chris Katko <ckatko gmail.com> writes:
On Monday, 3 September 2018 at 07:38:51 UTC, Chris Katko wrote:

 On Monday, 3 September 2018 at 06:28:38 UTC, bauss wrote:

 On Monday, 3 September 2018 at 06:25:23 UTC, bauss wrote:

 On Monday, 3 September 2018 at 03:19:39 UTC, Neia Neutuladh 
 wrote:

 On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko 
 wrote:

 This should be simple? All I want to do is load an entire 
 file, and access individual bytes. The entire thing. I 
 don't want to have know the file size before hand, or 
 "guess" and have a "maximum size" buffer.

 So far, all google searches for "dlang binary file read" 
 end up not working for me.

 Thank you.


 http://dpldocs.info/experimental-docs/std.file.read.1.html

 import std.file : read;
 auto bytes = read("filename");

 This gives you a void[], which you can cast to ubyte[] or 
 char[] or whatever you need.


 Or he could do readText() which returns a string, which in 
 turn will give a proper char array when casted.


 Actually ignore the casting thing, looking at readText it 
 takes a template parameter.

 So:

 char[] a = readText!(char[])("filename");


 Thanks, that works!

 But... I'm so confused by D's fifty different string types.

 I can run .strip() on a char[]. But I can't run 
 .replace('\n','?') ?

 So then I convert char[] to a temporary string and run replace 
 on that.

 but then writefln("%s") doesn't accept strings! Only char[].

   char []t = cast(char[])(c[i-15 .. i+1]).strip();
   string s = text(t); //s.replace('\n','?')
   writefln(" - [%s]", s); // fail

 main.d(89): Error: template std.array.replace cannot deduce 
 function from argument types !()(char[], char, char), 
 candidates are:
 /usr/include/dmd/phobos/std/array.d(2122):        
 std.array.replace(E, R1, R2)(E[] subject, R1 from, R2 to) if 
 (isDynamicArray!(E[]) && isForwardRange!R1 && isForwardRange!R2 
 && (hasLength!R2 || isSomeString!R2))
 /usr/include/dmd/phobos/std/array.d(2255):        
 std.array.replace(T, Range)(T[] subject, size_t from, size_t 
 to, Range stuff) if (isInputRange!Range && 
 (is(ElementType!Range : T) || isSomeString!(T[]) && 
 is(ElementType!Range : dchar)))


 What's going on here?


WAIT! This is my fault (not that I was saying it was "D's" fault, 
just that I was  confused).

it's not replace '' ''. It's replace "" "".  For some reason, I 
must have been thinking it was per-character (which is what I'm 
doing) so I should be using single quotes.

So I CAN run .replace("","") on a char[], just as I can a string. 
And THANK GOODNESS because I thought one of the major advantages 
of D was being relatively orthogonal/type agnostic and if I was 
going to have to remember "X() runs only on Y" for 3+ different 
string types that would be a nightmare!
Sep 03 2018
prev sibling parent rikki cattermole <rikki cattermole.co.nz> writes:
On 03/09/2018 7:38 PM, Chris Katko wrote:

 On Monday, 3 September 2018 at 06:28:38 UTC, bauss wrote:

 On Monday, 3 September 2018 at 06:25:23 UTC, bauss wrote:

 On Monday, 3 September 2018 at 03:19:39 UTC, Neia Neutuladh wrote:

 On Monday, 3 September 2018 at 03:04:57 UTC, Chris Katko wrote:

 This should be simple? All I want to do is load an entire file, and 
 access individual bytes. The entire thing. I don't want to have 
 know the file size before hand, or "guess" and have a "maximum 
 size" buffer.

 So far, all google searches for "dlang binary file read" end up not 
 working for me.

 Thank you.


 http://dpldocs.info/experimental-docs/std.file.read.1.html

 import std.file : read;
 auto bytes = read("filename");

 This gives you a void[], which you can cast to ubyte[] or char[] or 
 whatever you need.


 Or he could do readText() which returns a string, which in turn will 
 give a proper char array when casted.


 Actually ignore the casting thing, looking at readText it takes a 
 template parameter.

 So:

 char[] a = readText!(char[])("filename");


 
 Thanks, that works!
 
 But... I'm so confused by D's fifty different string types.


Only three. string, wstring and dstring. They are all aliases for 
immutable(Char)[].


 I can run .strip() on a char[]. But I can't run .replace('\n','?') ?


Replace is working on arrays, use " not '. There is a dedicated version 
for characters (tr).


 So then I convert char[] to a temporary string and run replace on that.


import std.stdio;
import std.array;

void main()
{
     char[] text = "123\nhi".dup;
     text = text.replace("\n", "?");
     text.writeln;
}


 but then writefln("%s") doesn't accept strings! Only char[].
 
    char []t = cast(char[])(c[i-15 .. i+1]).strip();
    string s = text(t); //s.replace('\n','?')
    writefln(" - [%s]", s); // fail


Looks ok to me:

import std.stdio;

void main()
{
     string s = "text";
     writefln(" - [%s]", s);
}
Sep 03 2018