• seany (36/36) Feb 14 2023 Hello
• Steven Schveighoffer (7/7) Feb 14 2023 ```d
• ProtectAndHide (16/53) Feb 15 2023 Building on previous response:

seany <seany uni-bonn.de> writes:

Hello

Consider the content of a file

````
First line \n
Second line ....
....
data data data data  ... last char

````

My goal is to find out whether the last character is a new line 
or not. Please not, it will be sufficient if this works on Linux.

More specifically I want to insert a new line at the end of the 
file. File.writeline inserts a line at the end of the _newly 
added line_.

Thus if I had


````
First line \n
Second line ....
....
data data data data  ... non-NL-char

````

and wanted to insert : `newline-word-word-word ... non-NLchar`

Via `file.writeln`, it would end up as

````
First line \n
Second line ....
....
data data data data  ... non-NL-char{no newline or whitespace 
here}Newline-word-word-word ... non-NLchar{newline}

````

This is not unexpected. But, I want to make sure, that my 
appending automatically adds a new line. However, it should not 
add empty lines.

One brute force method is to copy every line of the file to a 
temp file or in the RAM and then write back in the original file. 
I would like to avoid that if possible.

Thanks.

Steven Schveighoffer <schveiguy gmail.com> writes:

```d
myFile.seek(-1, SEEK_END);
ubyte c[1];
myFile.rawRead(c[]);
if(c[0] == '\n') // ends in newline
```

-Steve

ProtectAndHide <ProtectAndHide gmail.com> writes:

On Tuesday, 14 February 2023 at 18:30:05 UTC, seany wrote:
 Hello

 Consider the content of a file

 ````
 First line \n
 Second line ....
 ....
 data data data data  ... last char

 ````

 My goal is to find out whether the last character is a new line 
 or not. Please not, it will be sufficient if this works on 
 Linux.

 More specifically I want to insert a new line at the end of the 
 file. File.writeline inserts a line at the end of the _newly 
 added line_.

 Thus if I had


 ````
 First line \n
 Second line ....
 ....
 data data data data  ... non-NL-char

 ````

 and wanted to insert : `newline-word-word-word ... non-NLchar`

 Via `file.writeln`, it would end up as

 ````
 First line \n
 Second line ....
 ....
 data data data data  ... non-NL-char{no newline or whitespace 
 here}Newline-word-word-word ... non-NLchar{newline}

 ````

 This is not unexpected. But, I want to make sure, that my 
 appending automatically adds a new line. However, it should not 
 add empty lines.

 One brute force method is to copy every line of the file to a 
 temp file or in the RAM and then write back in the original 
 file. I would like to avoid that if possible.

 Thanks.

Building on previous response:

module test;
 safe:

import std;

void main()
{
     File myFile =  "somefile.txt";
     myFile.seek(-1, SEEK_END);

     ubyte[1] c;
     ()  trusted { myFile.rawRead(c[]); } ();

     if(ControlChar.lf == c[0]) // is this portable??
         writeln("yep, last char is a linefeed.");
     else
         writeln("nope. last char is not a linefeed.");

}