replacing a line in a txt file

[Anon]

Hi,
I'm trying to replace a line in a text file
and was looking for help on figuring out how. I've followed several leads but always get stumped when it comes to getting the the file pointer to stop after x return chars.

Thanks for you help,
Ben

[[deleted]]

First, there is no way of writing inside a file.
You can only append to a file, or overwrite a file completely.

Try using file() to read the textfile into an array.
$array = file('test.txt');
Then you can go through each line untill you find the line you want to replace, and replace it
if ($array[456]=="this should be replaced")
{
$array[456]="New line";
};

then you can use the fopen() and fwrite() commands to write the array back to disk as a textfile.

[Anon]

Well first of all i guess i have to proove you wrong :/

$fp=fopen($filename,"r");
fseek($fp,100);
fwrite($fp,"DOGTHIS");
fclose($fp);

That will insert "dogthis" into lines.txt overwriting the text in the way.

Also right now i am using the array method but its way too slow, i'm dealing with a rather large file and writing it to an array to overwrite 1 line is insane.

Thanks,
Ben

[toma42]

I think vincent's way is going to be the best. Writting to the middle of a file is not easy, especially if you want to replace a variable length line with a new line. The array method will, I think, be the best way for this.

Good luck

[[deleted]]

I assume you mean 'r+', not 'r'.

(damn, forgot about that one)
Anyway, that's pretty much useless unless your lines are of a fixed length.

[trellie]

personally i would even use the array method... since this can use a huge amount of memory (if the file is bigger then 8Mb a default php installation will halt due to a fatal error)

i'd read line by line instead of loading it to memory in one piece.

[Anon]

Yah thanks
i realized i was being retarded :/, sorta sucks

[[deleted]]

That's also possible, but then you'd have to lock the file, open a new file, read-write line by line untill the file is done,
then erase the original file, and move the new file to the old name...

How often do you edit text files of more than 100k?

[[deleted]]

Ah, so I still get to come out of this thread as being the total PHP god? :-)

yeeeheee!

[kparker]

Well first of all i guess i have to proove you wrong :/

Guess again; that would have to be "r+" mode to allow writing as well as reading.

It actually sounds like you need a database, not a text file.

[kparker]

Ah, so I still get to come out of this thread as being the total PHP
god? :-)

Nope, not this time--I'm the first one to say Maybe You Should Use A Database. :-) :-) :-)

[[deleted]]

Aha, but using a database mayb not be required if this is a one-off operation. :-)

[Anon]

well when your told to do a job a certain way, you don't really have a choice :/