maximum allocation using malloc

This is a discussion on maximum allocation using malloc within the C Programming forums, part of the General Programming Boards category; how much memory allocation can we allocate using malloc. what is the maximum value in bytes.....

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    maximum allocation using malloc

    how much memory allocation can we allocate using malloc. what is the maximum value in bytes..

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    C++まいる!Cをこわせ! Elysia's Avatar
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    As much free virtual memory in a contiguous space that is available.
    In other words, it's operating system dependant and it's also dependant on how much virtual memory you've already used and how fragmented the virtual memory is.
    No hard limit.
    But don't go abusing it because of that.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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    Depends on the OS-model, which in turn depends on the processor architecture as well as implementation details in the OS itself [e.g. an OS may well decide to use an arbitrary limit that is lower than what the processor can technically cope with].

    Usual numbers are:
    16-bit DOS - 64KB.
    32-bit Linux - 1 or 3 GB.
    32-bit Windows 2GB.
    64-bit Windows 16TB.
    64-bit Linux 16TB.

    Those are the limits for the virtual address space, of course, if there isn't enough RAM and Swap-space, the limitation of RAM/Swap-space will stop you before the physical memory limit does.

    --
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    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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    thank u guys.. thanks a lot

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    C++まいる!Cをこわせ! Elysia's Avatar
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    Do remember that malloc will fail is there isn't enough free contiguous virtual memory available.
    Also remember that malloc will fail if the OS says no. The OS might say no if there simply isn't enough available memory, as well as other factors.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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