Why does C have the best file API

Post by SvenL » Sun, Mar 01, 2026, 10:37 PM UTC

Const-me wrote: post #8

I think C# standard library is better. You can do same unsafe code as in C, SafeBuffer.AcquirePointer method then directly access the memory. Or you can do safer and slightly slower by calling Read or Write methods of MemoryMappedViewAccessor. All these methods are in the standard library, i.e. they work on all platforms. The C code is specific to POSIX; Windows supports memory mapped files too but the APIs are quite…

Post by dekhn » Sun, Mar 01, 2026, 10:48 PM UTC

userbinator wrote: post #18

It still works if the file doesn't fit in RAM No it doesn't. If you have a file that's 2^36 bytes and your address space is only 2^32, it won't work. On a related digression, I've seen so many cases of programs that could've handled infinitely long input in constant space instead implemented as some form of "read the whole input into memory", which unnecessarily puts a limit on the input length.

Post by dekhn » Sun, Mar 01, 2026, 10:50 PM UTC

okanat wrote: post #32

I guess the author didn't use that many other programming languages or OSes. You can do the same even in garbage collected languages like Java and C# and on Windows too. https://docs.oracle.com/javase/8/docs/api/java/nio/MappedByt... https://learn.microsoft.com/en-us/dotnet/api/system.io.memor... https://learn.microsoft.com/en-us/windows/win32/memory/creat... Memory mapping is very common.

Post by phoronixrly » Sun, Mar 01, 2026, 10:53 PM UTC

Dwedit wrote: post #12

Using mmap means that you need to be able to handle memory access exceptions when a disk read or write fails. Examples of disk access that fails includes reading from a file on a Wifi network drive, a USB device with a cable that suddenly loses its connection when the cable is jiggled, or even a removable USB drive where all disk reads fail after it sees one bad sector. If you're not prepared to handle a memory acces…

Post by teunispeters » Sun, Mar 01, 2026, 11:13 PM UTC