Replacing some bytes in middle of file

Does anyone have a method of replacing bytes inside a text file
at the position determined by doing an fseek() ?
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The 'a' mode in fopen() always defaults to appending to the end of
file, and there doesn't appear to be any other listed way of, say,
replacing a chunk of data in a fixed-record-length text file.
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Can I use popen() to achieve this, maybe ?

TIA

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Chris

 

Or you could extract the contents into a string, replace the necessary characters and replace the data in the file with the new string!

 

Thanks, rohan.
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Yes, that's what I figured. Using file_get_contents() and explode().
Then adjust the element in the array and use implode() and
file_put_contents to restore it.
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Trouble with that solution is that you need the file locked for a "long" time
doing the overhead work, otherwise someone is reading the old data.
If there was a way of simply writing to the middle, you wouldn't need the
file at all until you were actually ready to write.
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Shame there's no cleaner solution ! (Genuine random record writes
to FRL files)
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Chris

 

Learn regex like ereg_replace, preg_replace,str_replace etc.

 

I'm OK with that, sastro ! The string manipulation stuff
doesn't faze me at all. It was the file handling issue.
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Like: You have a textfile of, say, "customers". It's fixed record
length with delimit by length and padding. One customer changes
their email address so you need to swap out that one FL record
for another. With random access file writes, using an offset, that's
a no-brainer. In PHP, it's a tad more code-heavy. That was all.


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Chris