in reply to What is the point of a+ and w+ when opening files?

And in a similar vein what would be the point of opening a file in read/write/truncate (w+) mode possibly be?

Yes, since w+ mode clobbers the file first, this is not usually a particularly useful mode. But a+ and r+ certainly do have their uses, for example, if you want any kind of random access to read/write the data in the file (e.g. updating fixed-length records) - though personally I've never done this directly, as this is usually the job of a library that handles that particular data format. However, see the last code example in my node here, in particular in combination with the notes on flock above it, this can be useful in some cases.

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Re^2: What is the point of a+ and w+ when opening files?
by cavac (Prior) on Sep 09, 2024 at 14:10 UTC

    though personally I've never done this directly, as this is usually the job of a library that handles that particular data format.

    Ah, yes, the luxuries of modern desktop computing. I grew up with Commodore computers (VIC20, C64, Amiga), and nowadays i sometimes work with Microcontrollers of the Arduino family. When you are low on memory (="always"), you tend to code as low level as possible.

    Heck, for one of my projects i'm talking to the memory chips directly via I2C, because the corresponding library would require ~200(!!!!!) bytes of RAM. When you only got 2048 of those buggers in total, you tend to turn into Scrooge McDuck.

    But even in some of my more recent data extraction projects i had to use random access for fixed size records.

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