I am reading a binary file and I am using the tell() function to get the specific position of a location. I am reading the file in binary mode:

open( FH , "+<" , $source ) or die "Can not open file: $source $!\n";
binmode(FH);

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I am moving the pointer to the desired position with string condition and using:

$position = tell(FH)

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In order to get the pointer position int. Then I use SEEK to move to the position that I have previously marked by doing:

seek( FH , $position , SEEK_SET );

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Where I am issuing the commang: 

write( FH, $example , $example_size )
    or die "Couldn't write at FH : $!\n";

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I was browsing over the internet and I found that the opposite of read() is not write(). But later on trying to find a solution to my problem I came across with the Perl man page perlapio − perl’s IO abstraction interface. and also perlclib.

Both of the web pages state that the alternative of fwrite() in C is write():

fwrite(p, size, n, stream) PerlIO_write(perlio, buf, numbytes)

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I tried to apply that in my code and I keep getting this error:

Useless use of a constant (FH) in void context at test.pl line 193.

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I looked online what is the error and I found that it can not open the file properly. I do have a die condition on open and also I have a few printf() conditions to test if the file is opening and they are coming up. So at this point I assume it is a wrong syntax with the write() function. Are there any alternatives that I could use?

Thanks in advance for your time and effort.

In reply to Writing at specific position and length in binary file. by thanos1983

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