• hridyansh thakur (1/1) Sep 06 2018 how to read a file line by line in D
• Arun Chandrasekaran (20/21) Sep 06 2018 std.stdio.File.byLine()
• rikki cattermole (16/38) Sep 06 2018 Ranges will be far too advanced of a topic to bring up at this stage.
• Steven Schveighoffer (10/53) Sep 06 2018 Ugh, don't do that, it will read the unknown-length file into RAM all at...
• Steven Schveighoffer (11/67) Sep 06 2018 ugh, I didn't think this through. This works:

hridyansh thakur <hridyanshthakur gmail.com> writes:

how to read a file line by line in D

Arun Chandrasekaran <aruncxy gmail.com> writes:

On Thursday, 6 September 2018 at 16:13:42 UTC, hridyansh thakur 
wrote:
 how to read a file line by line in D

std.stdio.File.byLine()

Refer the doc here: 
https://dlang.org/library/std/stdio/file.by_line.html

An example from the doc:

```
import std.algorithm, std.stdio, std.string;
// Count words in a file using ranges.
void main()
{
     auto file = File("file.txt"); // Open for reading
     const wordCount = file.byLine()            // Read lines
                           .map!split           // Split into words
                           .map!(a => a.length) // Count words per 
line
                           .sum();              // Total word count
     writeln(wordCount);
}
```

rikki cattermole <rikki cattermole.co.nz> writes:

On 07/09/2018 4:17 AM, Arun Chandrasekaran wrote:
 On Thursday, 6 September 2018 at 16:13:42 UTC, hridyansh thakur wrote:
 how to read a file line by line in D

 
 std.stdio.File.byLine()
 
 Refer the doc here: https://dlang.org/library/std/stdio/file.by_line.html
 
 An example from the doc:
 
 ```
 import std.algorithm, std.stdio, std.string;
 // Count words in a file using ranges.
 void main()
 {
      auto file = File("file.txt"); // Open for reading
      const wordCount = file.byLine()            // Read lines
                           
.map!split           // Split into words
                            .map!(a => a.length) //
Count words per line
                           
.sum();              // Total word count
      writeln(wordCount);
 }
 ```

Ranges will be far too advanced of a topic to bring up at this stage.

So something a little more conventional might be a better option:

---
import std.file : readText;
import std.array : split;
import std.string : strip;

string text = readText("file.txt");
string[] onlyWords = text.split(" ");

uint countWords;
foreach(ref word; onlyWords) {
	word = word.strip();
	if (word.length > 0)
		countWords++;
}
---

Steven Schveighoffer <schveiguy gmail.com> writes:

On 9/6/18 1:07 PM, rikki cattermole wrote:
 On 07/09/2018 4:17 AM, Arun Chandrasekaran wrote:
 On Thursday, 6 September 2018 at 16:13:42 UTC, hridyansh thakur wrote:
 how to read a file line by line in D

 std.stdio.File.byLine()

 Refer the doc here: https://dlang.org/library/std/stdio/file.by_line.html

 An example from the doc:

 ```
 import std.algorithm, std.stdio, std.string;
 // Count words in a file using ranges.
 void main()
 {
      auto file = File("file.txt"); // Open for reading
      const wordCount = file.byLine()            // Read lines
                           
.map!split           // Split into words
                            .map!(a => a.length) //
Count words per line
                           
.sum();              // Total word count
      writeln(wordCount);
 }
 ```

 
 Ranges will be far too advanced of a topic to bring up at this stage.
 
 So something a little more conventional might be a better option:
 
 ---
 import std.file : readText;
 import std.array : split;
 import std.string : strip;
 
 string text = readText("file.txt");
 string[] onlyWords = text.split(" ");
 
 uint countWords;
 foreach(ref word; onlyWords) {
      word = word.strip();
      if (word.length > 0)
          countWords++;
 }
 ---

Ugh, don't do that, it will read the unknown-length file into RAM all at 
once.

foreach(word; File("file.txt").byLine)
{
    word = word.strip();
    if(word.length > 0) countWords++;
}

That will buffer one line at a time and achieve the same results.

-Steve

Steven Schveighoffer <schveiguy gmail.com> writes:

On 9/6/18 2:30 PM, Steven Schveighoffer wrote:
 On 9/6/18 1:07 PM, rikki cattermole wrote:
 On 07/09/2018 4:17 AM, Arun Chandrasekaran wrote:
 On Thursday, 6 September 2018 at 16:13:42 UTC, hridyansh thakur wrote:
 how to read a file line by line in D

 std.stdio.File.byLine()

 Refer the doc here: 
 https://dlang.org/library/std/stdio/file.by_line.html

 An example from the doc:

 ```
 import std.algorithm, std.stdio, std.string;
 // Count words in a file using ranges.
 void main()
 {
      auto file = File("file.txt"); // Open for reading
      const wordCount = file.byLine()            // Read lines
                           
.map!split           // Split into words
                            .map!(a => a.length) //
Count words per line
                           
.sum();              // Total word count
      writeln(wordCount);
 }
 ```

 Ranges will be far too advanced of a topic to bring up at this stage.

 So something a little more conventional might be a better option:

 ---
 import std.file : readText;
 import std.array : split;
 import std.string : strip;

 string text = readText("file.txt");
 string[] onlyWords = text.split(" ");

 uint countWords;
 foreach(ref word; onlyWords) {
      word = word.strip();
      if (word.length > 0)
          countWords++;
 }
 ---

 
 Ugh, don't do that, it will read the unknown-length file into RAM all at 
 once.
 
 foreach(word; File("file.txt").byLine)
 {
     word = word.strip();
     if(word.length > 0) countWords++;
 }
 
 That will buffer one line at a time and achieve the same results.

ugh, I didn't think this through. This works:

foreach(line; File("file.txt").byLine)
{
    foreach(word; line.split(" "))
    {
    	word = word.strip();
    	if(word.length > 0) countWords++;
    }
}

-Steve