_open(), _read(), etc

This is a discussion on _open(), _read(), etc within the C++ Programming forums, part of the General Programming Boards category; Are functions like _open(), _read(), and _lseek() C functions only? I assume they are since they are in io.h. I ...

  1. #1
    carry on JaWiB's Avatar
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    _open(), _read(), etc

    Are functions like _open(), _read(), and _lseek() C functions only? I assume they are since they are in io.h. I was wondering if C++ has a better way to read from files than fstreams, since I have always had problems with them (just too hard to use) Mainly the function I would like for C++ is _lseek() and I don't know of any equivalent...Or are these functions ok to use in C++ programs? File I/O has always been a problem for me and I just discovered these and it made it 1000% easier for me...
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  2. #2
    twm
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    >Are functions like _open(), _read(), and _lseek() C functions only?
    No, you can use them with C++ too.

    >I was wondering if C++ has a better way to read from files than fstreams
    You can use C++ streams, C FILE pointers, or Unix style file descriptors if your system supports them. I find FILE pointers to be the most flexible for my purposes while still maintaining portability, but I don't use C++ much. If you don't use stream objects then niceties like std::string will give you trouble.

    >Mainly the function I would like for C++ is _lseek() and I don't know of any equivalent.
    Stream objects have seekp and seekg member functions that do basically the same thing as lseek.
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    carry on JaWiB's Avatar
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    If you don't use stream objects then niceties like std::string will give you trouble.
    Working with char* (s) is not a real problem with what I'm trying to do atm, so I think I will be ok. I guess my real question was "Are these still ok to use for C++"...It still feels wrong mixing a .h header with the new ones (these functions aren't found in any new headers, are they?) , but streams make me so frustrated I don't want to consider using them
    "Think not but that I know these things; or think
    I know them not: not therefore am I short
    Of knowing what I ought."
    -John Milton, Paradise Regained (1671)

    "Work hard and it might happen."
    -XSquared

  4. #4
    twm
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    >I guess my real question was "Are these still ok to use for C++"
    Of course. Most C code is also valid C++ code.

    >It still feels wrong mixing a .h header with the new ones
    You're listening too hard to the portability lovers. The ANSI C headers are placed in namespace std by putting them in the <c*> headers, but you can still access the old ones and you will be until the end of time as long as C++ claims compatibility with C. Nonstandard headers will usually end with .h or something equivalent, so unless you always program in 100% ANSI you'll use them.
    The information given in this message is known to work on FreeBSD 4.8 STABLE.
    *The above statement is false if I was too lazy to test it.*
    Please take note that I am not a technical writer, nor do I care to become one.
    If someone finds a mistake, gleaming error or typo, do me a favor...bite me.
    Don't assume that I'm ever entirely serious or entirely joking.

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