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How to define a long long integer in C++ (I use Linux, 32 bit)

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How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 18th, 2008

Hello,

Firstly I better warn you I'm quite new to C++ and to Linux so I'm sorry if my terminology/general understanding of how things work is a bit confused.

I've downloaded a code which is in C which is helpful for a course I'm doing on stellar structure, but I'd like to use it with C++. Everything translates just fine apart from the the definition of the maximum of a number as a "long long int". Apparently C++ doesn't support this form.

I use Linux (32 bit) and I'd like to be able to use that integer in my programme. Is there a library or particular compiler I can use so that I can have numbers like that in the programme, or is there a solution I can find without downloading anything? I currently use g++. My first thought was to turn the number into a double, as that stopped the errors appearing, but after a conversation with a more computer-literate friend, I've realised how ineffective that was (just to give you an idea of my level of understanding of these things).

If there's something I need to download, please could you send me a link, and ideally give me a bit of instruction as to exactly what I need to do with it once I've downloaded it, and what I'd need to include in the programme to use it (as I said, I'm very inexperienced with both the operating system and the programming language!)

Thanks!

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 18th, 2008

I thought most modern c and c++ compilers supported some form of 64-bit integers. Try just "long long" instead of "long long int".

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 18th, 2008

Thanks for the reply. I've tried that, and it doesn't seem to help. I just get the error "integer constant is too large for "long" type.

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 18th, 2008

Please post your program -- maybe there is something else wrong with it. I don't have a *nix os so I can't really help you much.

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 18th, 2008

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
//The smallest non-zero number and the number of significant figures
 
    const float         tiny_sp     = 3.4e-38F;
 
    const double        tiny_dp     = 1.7e-308;
 
    const long double   tiny_qp     = tiny_dp;
 
    const short int     sig_fig_sp  = 7;
 
    const short int     sig_fig_dp  = 15;
 
    const short int     sig_fig_qp  = sig_fig_dp;
 
    const float         eps_sp      = 1E-6;
 
    const double        eps_dp      = 1E-15;
 
    const long double   eps_qp      = eps_dp;
 
//The largest number for given precision
 
    const float         biggest_sp  = 3.4e38F;
 
    const double        biggest_dp  = 1.7e308;
 
    const long double   biggest_qp  = biggest_dp;
 
    const short int     biggest_i2  = 32767;
 
    const long int      biggest_i4  = 2147483647;
 
    const long long int	biggest_i8  = 9223372036854775807;
//The smallest non-zero number and the number of significant figures

    const float         tiny_sp     = 3.4e-38F;

    const double        tiny_dp     = 1.7e-308;

    const long double   tiny_qp     = tiny_dp;

    const short int     sig_fig_sp  = 7;

    const short int     sig_fig_dp  = 15;

    const short int     sig_fig_qp  = sig_fig_dp;

    const float         eps_sp      = 1E-6;

    const double        eps_dp      = 1E-15;

    const long double   eps_qp      = eps_dp;

//The largest number for given precision

    const float         biggest_sp  = 3.4e38F;

    const double        biggest_dp  = 1.7e308;

    const long double   biggest_qp  = biggest_dp;

    const short int     biggest_i2  = 32767;

    const long int      biggest_i4  = 2147483647;

    const long long int	biggest_i8  = 9223372036854775807;

That's the top part of the code I'm using for defining. I link several other C++ codes together to form the overall programme, but when I try to do that the errors which come up are all related to the constant defined in the bottom line of this.

Last edited by Ancient Dragon; Dec 18th, 2008 at 10:16 pm. Reason: correct code tags

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 19th, 2008

That value is correct as maximum for signed long long.

What specific compiler are you using?

Look at the include file <limits.h> to see what types and their ranges are available in that compiler.

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 19th, 2008

Try putting "LL" after the literal value, as in:
const long long int biggest_i8 = 9223372036854775807LL;

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 19th, 2008

Alas, long long int is not a standard type in C++ at the moment. Moreover, the C++ (and C) standard garantees that long number type is not less that ordinar type - that's all (for example, sizeof(long long int) >= sizeof(long int) , but not sizeof(long long) > sizeof(long) ).

Therefore it was a very careless project decision to rely upon non-standard long long int POD type with huge values range.

There are arbitrary precision integer arithmetics libraries for C++ and C but it seems you need too serious code refactoring to use those libraries (it's easier to move to double type).

If it's a very long (long long

) code use Windows+VC++ compiler with 64-bit long long type extension. Regrettably I don't know proper linux compilers with 64-bit long long (ask linux guru)...

Last edited by ArkM; Dec 19th, 2008 at 4:29 am.

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

Dec 19th, 2008

Thanks for the information.

Could anyone suggest a Linux compiler with a 64-bit long long type extension? I've been having a look and can't seem to find anything. If anyone has any further ideas for how to fix this please let me know.

Thanks

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Re: How to define a long long integer in C++ (I use Linux, 32 bit)

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Dec 19th, 2008

Doesn't the latest version of g++ support it? Maybe you just need to download the lastest version. GNU is usually pretty good at keeping those compilers up-to-date.

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