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Start structures like in C++

vtrx

How do I start the values ​​as in the example C++ code?

struct Gains{
    uint8_t totalGain         = FORCE_FEEDBACK_MAXGAIN;
   uint8_t constantGain      = FORCE_FEEDBACK_MAXGAIN;
   uint8_t rampGain          = FORCE_FEEDBACK_MAXGAIN;
   uint8_t squareGain        = FORCE_FEEDBACK_MAXGAIN;
   uint8_t sineGain          = FORCE_FEEDBACK_MAXGAIN;
   uint8_t triangleGain      = FORCE_FEEDBACK_MAXGAIN;
   uint8_t sawtoothdownGain  = FORCE_FEEDBACK_MAXGAIN;
   uint8_t sawtoothupGain    = FORCE_FEEDBACK_MAXGAIN;
   uint8_t springGain        = FORCE_FEEDBACK_MAXGAIN;
   uint8_t damperGain        = FORCE_FEEDBACK_MAXGAIN;
   uint8_t inertiaGain       = FORCE_FEEDBACK_MAXGAIN;
   uint8_t frictionGain      = FORCE_FEEDBACK_MAXGAIN;
   uint8_t customGain        = FORCE_FEEDBACK_MAXGAIN;
};

struct EffectParams{
    int32_t springMaxPosition = 0;
    int32_t springPosition = 0;

    int32_t damperMaxVelocity = 0;
    int32_t damperVelocity = 0;

    int32_t inertiaMaxAcceleration = 0;
    int32_t inertiaAcceleration = 0;

    int32_t frictionMaxPositionChange = 0;
    int32_t frictionPositionChange = 0;
};
   //force feedback gain
   struct Gains* m_gains;

   //force feedback effect params
   struct EffectParams* m_effect_params;

  • 0

    If you're writing C++, just do it.

    If you're not, you can't.

  • 0

    >    struct EffectParams* m_effect_params;

    Note that that line declares a pointer, not the structure itself, so it doesn't initialize anything.  malloc() won't either, but C++'s "new" might?

    This comes close. sort of:


    struct Gains{
      uint8_t totalGain;
      uint8_t constantGain;
      uint8_t rampGain ;
      uint8_t squareGain;
      uint8_t sineGain ;
      uint8_t triangleGain;
      uint8_t sawtoothdownGain;
      uint8_t sawtoothupGain;
      uint8_t springGain;
      uint8_t damperGain;
      uint8_t inertiaGain;
      uint8_t frictionGain;
      uint8_t customGain;
    };

    #define Gains_inited(x) struct Gains x = { \
       .totalGain         = FORCE_FEEDBACK_MAXGAIN, \
       .constantGain      = FORCE_FEEDBACK_MAXGAIN, \
       .rampGain          = FORCE_FEEDBACK_MAXGAIN, \
       .squareGain        = FORCE_FEEDBACK_MAXGAIN, \
       .sineGain          = FORCE_FEEDBACK_MAXGAIN, \
       .triangleGain      = FORCE_FEEDBACK_MAXGAIN, \
       .sawtoothdownGain  = FORCE_FEEDBACK_MAXGAIN, \
       .sawtoothupGain    = FORCE_FEEDBACK_MAXGAIN, \
       .springGain        = FORCE_FEEDBACK_MAXGAIN, \
       .damperGain        = FORCE_FEEDBACK_MAXGAIN, \
       .inertiaGain       = FORCE_FEEDBACK_MAXGAIN, \
       .frictionGain      = FORCE_FEEDBACK_MAXGAIN, \
       .customGain        = FORCE_FEEDBACK_MAXGAIN, \
      }

    Gains_inited(*m_gains);

  • 0 in reply to vtrx
    vtrx said:
    How do I start values ​​in C?

    Like I said: you don't.  If you strongly believe you need that feature, you will have to write your code in C++.  It's ultimately as simple as that.

    Nor is it ever called "start".  The C++ feature you're trying to use is called a default value.  It's used by the constructor, for those members of the struct the user didn't supply their own initializer values, for .  C simply doesn't have that entire set of features.