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digitalmars.D.learn - Any additions for write-to-file short program

reply pascal111 <judas.the.messiah.111 gmail.com> writes:
In next program that rewrites original written texts into new 
files, I see that it may need some additions or we can accept it 
like this because it's just a simple program that achieve its 
task and doesn't need any philosophical additions.

Example:

Original text:

Learning C doesn't impact bad on C++. In theoretical speaking we 
think that C++ is C with some new features, but these features 
maybe tends to some high level, and working with C is more 
difficult than direct learning of C++, because last one provides 
features or tools make us pass some low level ways we have to use 
in C to do same tasks, so, the work with C impact good on 
learning C++ because we see everything with its real nature in C.

New produced text in new file:

Learning C doesn't impact bad on C++. In theoretical speaking we 
think that C++ is C with some new features, but these features 
maybe tends to some high level, and working with C is more 
difficult than direct learning of C++, because last one provides 
features or tools make us pass some low level ways we have to use 
in C to do same tasks, so, the work with C impact good on 
learning C++ because we see everything with its real nature in C.




Code:

// D programming language

import std.stdio;
import std.string;

int main()
{

string s;
char[] f;


try{
write("Enter file name and path: ");
readln(f);
f=strip(f);}

catch(Exception err){
stderr.writefln!"Warning! %s"(err.msg);}


     File file = File(f, "r");
     File file2 = File("output_x.txt", "w");

     while (!file.eof()) {
           s = chomp(file.readln());
           file2.writeln(s);
        }

     file.close();
     file2.close();

return 0;

}
Nov 18 2021
next sibling parent reply "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Thu, Nov 18, 2021 at 10:20:48PM +0000, pascal111 via Digitalmars-d-learn
wrote:

 In next program that rewrites original written texts into new files, I
 see that it may need some additions or we can accept it like this
 because it's just a simple program that achieve its task and doesn't
 need any philosophical additions.


I assume there's a reason you're reading the input file by line instead
of just copying it using larger fixed-size blocks?  Perhaps you have in
mind some kind of line-based filtering or processing eventually?

Because for copying a file, using a large, fixed-size block will work
much faster. Not to mention the code will be simpler. For example:

	auto inputFile = File(inputFilename, "r");
	auto outputFile = File(outputFilename, "w");

	enum bufferSize = 8194;
	inputFile.byChunk(bufferSize)	// read input in blocks of 8194 bytes
		.copy(outputFile.lockingBinaryWriter); // copy each block into output file


T

-- 
Javascript is what you use to allow third party programs you don't know
anything about and doing you know not what to run on your computer. --
Charles Hixson
Nov 18 2021
parent reply pascal111 <judas.the.messiah.111 gmail.com> writes:
On Thursday, 18 November 2021 at 23:09:28 UTC, H. S. Teoh wrote:

 On Thu, Nov 18, 2021 at 10:20:48PM +0000, pascal111 via 
 Digitalmars-d-learn wrote:

 In next program that rewrites original written texts into new 
 files, I see that it may need some additions or we can accept 
 it like this because it's just a simple program that achieve 
 its task and doesn't need any philosophical additions.


 I assume there's a reason you're reading the input file by line 
 instead of just copying it using larger fixed-size blocks?  
 Perhaps you have in mind some kind of line-based filtering or 
 processing eventually?

 Because for copying a file, using a large, fixed-size block 
 will work much faster. Not to mention the code will be simpler. 
 For example:

 	auto inputFile = File(inputFilename, "r");
 	auto outputFile = File(outputFilename, "w");

 	enum bufferSize = 8194;
 	inputFile.byChunk(bufferSize)	// read input in blocks of 8194 
 bytes
 		.copy(outputFile.lockingBinaryWriter); // copy each block 
 into output file


 T



When I compiled the code after adding yours, I found this error 
message:

"untitled20.d:24:8: error: no property 'copy' for type 'ByChunk'
    24 |        .copy(outputFile.lockingBinaryWriter); // copy 
each block into output file
       |        ^
"
Nov 19 2021
next sibling parent Imperatorn <johan_forsberg_86 hotmail.com> writes:
On Friday, 19 November 2021 at 22:21:52 UTC, pascal111 wrote:

 On Thursday, 18 November 2021 at 23:09:28 UTC, H. S. Teoh wrote:

 [...]



 When I compiled the code after adding yours, I found this error 
 message:

 "untitled20.d:24:8: error: no property 'copy' for type 'ByChunk'
    24 |        .copy(outputFile.lockingBinaryWriter); // copy 
 each block into output file
       |        ^
 "


Did you import std.algorithm?
Nov 19 2021
prev sibling parent reply "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Fri, Nov 19, 2021 at 10:21:52PM +0000, pascal111 via Digitalmars-d-learn
wrote:
[...]

 When I compiled the code after adding yours, I found this error message:
 
 "untitled20.d:24:8: error: no property 'copy' for type 'ByChunk'
    24 |        .copy(outputFile.lockingBinaryWriter); // copy each block
 into output file
       |        ^
 "


import std.algorithm;


T

-- 
It is impossible to make anything foolproof because fools are so ingenious. --
Sammy
Nov 19 2021
parent pascal111 <judas.the.messiah.111 gmail.com> writes:
On Friday, 19 November 2021 at 23:05:03 UTC, H. S. Teoh wrote:

 On Fri, Nov 19, 2021 at 10:21:52PM +0000, pascal111 via 
 Digitalmars-d-learn wrote: [...]

 When I compiled the code after adding yours, I found this 
 error message:
 
 "untitled20.d:24:8: error: no property 'copy' for type 
 'ByChunk'
    24 |        .copy(outputFile.lockingBinaryWriter); // copy 
 each block
 into output file
       |        ^
 "


 import std.algorithm;


 T


Thanks! it works now.

code:

// D programming language

import std.stdio;
import std.string;
import std.algorithm;

int main()
{

string s;
char[] f;


try{
write("Enter file name and path: ");
readln(f);
f=strip(f);


File inputFile = File(f, "r");
File outputFile = File("output_x", "w");

enum bufferSize = 8194;
inputFile.byChunk(bufferSize)	// read input in blocks of 8194 
bytes
        .copy(outputFile.lockingBinaryWriter); // copy each block 
into output file


inputFile.close();
outputFile.close();
}


catch(Exception err){
stderr.writefln!"Warning! %s"(err.msg);
return 1;
}



return 0;

}
Nov 19 2021
prev sibling parent Stanislav Blinov <stanislav.blinov gmail.com> writes:
On Thursday, 18 November 2021 at 22:20:48 UTC, pascal111 wrote:

 In next program that rewrites original written texts into new 
 files, I see that it may need some additions or we can accept 
 it like this because it's just a simple program that achieve 
 its task and doesn't need any philosophical additions.


If "the task" is to copy a file, then this program, as presented, 
may fail at it. If you're going to do any exception handling at 
all, a question must be answered: what to do in case the 
algorithm is interrupted before completing? I.e. if the `while` 
loop throws an exception, which it can do on any line except for 
braces. Is it acceptable to leave the output file containing only 
part of input data, perhaps even no data at all? Or should you 
catch the exception and delete the output file? Will that even be 
possible?..
Nov 18 2021