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any significant difference

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  • 07-03-2019 6:03pm
    #1
    iLikeWaffles
    Registered Users Posts: 4,325 ✭✭✭


    Feel a bit silly asking in a new thread but just wondering if there is any significance in declaring a float like this:

    float whatever = 0.f;
    or
    float whatever = 0.0f;

    besides the dropped zero after the decimal is there any advantage to doing the first?


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    #2
    28064212
    Registered Users Posts: 10,614 ✭✭✭✭28064212


    Stating the language would help. In C#, the former is a syntax error. Assuming it's Java, you could just do this to test: 
    float x = 0.F;
float y = 0.0F;
System.out.print(x == y);

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    #3
    iLikeWaffles
    Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    28064212 wrote: »
    Stating the language would help. In C#, the former is a syntax error. Assuming it's Java, you could just do this to test: 
    float x = 0.F;
float y = 0.0F;
System.out.print(x == y);

    It's C++


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    #4
    Anima
    Registered Users Posts: 3,945 ✭✭✭Anima


    There isn't a difference no.


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    #5
    iLikeWaffles
    Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    I'm just thinking out loud here and a little busy porting code to set up a project.
    Just to followup. Lets say I have:
    #define pi   3.14159265358979323

float 2pi = 0.00f;

2pi = 2*pi;

    Would that make 
    2pi == 6.28
    or 
    2pi == 6.28318530717958646


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    #6
    Colonel Panic
    Registered Users Posts: 2,022 ✭✭✭Colonel Panic


    You can just test these things for yourself!!

    Why would it round the float to two decimal places???


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    #7
    iLikeWaffles
    Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    Colonel Panic wrote: »
    You can just test these things for yourself!!

    Why would it round the float to two decimal places???

    As I said I'm a little busy and thinking out loud. Why have a forum if that's the case???


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    #8
    smacl
    Moderators, Society & Culture Moderators Posts: 15,750 Mod ✭✭✭✭smacl


    iLikeWaffles wrote: »
    I'm just thinking out loud here and a little busy porting code to set up a project.
    Just to followup. Lets say I have:
    #define pi   3.14159265358979323

float 2pi = 0.00f;

2pi = 2*pi;

    Would that make 
    2pi == 6.28
    or 
    2pi == 6.28318530717958646

    Neither.

    Edit:

    1) 2pi is not a legal variable name in C++
    2) If you were to use a legal variable name, e.g. TwoPi the value would be 6.28318548 which is limited by that fact that a float is only 4 bytes
    3) You should avoid == equality checks on doubles and floats in C++ for values other than zero, see https://stackoverflow.com/questions/18971533/c-comparison-of-two-double-values-not-working-properly Use an epsilon value or similar.


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