Strange behaviour when passing values from a float array to a double array (C, C++) -

i developing application uses ni-daq , below methods given provider.

void somemethod(calibration *cal, float myarray[], float result[])  {     newmethod(&cal->rt,myarray,result,cal->cfg.tempcompenabled); }  void newmethod(rtcoefs *coefs, double myarray[],float result[],bool tempcomp)  { float newmyarray[6];     unsigned short i;      (i=0; < 6; i++)      {          newmyarray[i]=myarray[i];     }  } 

i call somemethod(), providing array 6 elements ( [6] ) both myarray[] , result[]. can see in code, afterwards newmethod() called, , float myarray[6] passed double myarray[] argument (i not understand why developer of code chose use double array, since array declared inside newmethod() float type).

now here comes problem: inside loop, values passed without problem, when fourth , fifth values passed newmyarray[], receives "-1.#inf0000" both values. @ first glance, thought garbage value, "-1.#inf0000" there @ every execution.

i know c language can tricky sometimes, not know why happening...

the second parameter newmethod has type double *. pass value of type float *.

in c++, or in c if there prototype of newmethod in scope, must generate compilation error. there no implicit conversion between pointer types , except void *.

however, in c, if there no prototype in scope may no warning; undefined behaviour @ runtime because function called arguments of different type (after default argument promotions) defined.

if there non-prototype declaration of newmethod in scope no warning; if there no declaration @ in c89 code legal (i.e. warning optional) , in c99 must warn newmethod called without being declared.

(so important whether c program or c++ program).

if in c , getting no warning, add prototype before this:

void newmethod(rtcoefs *coefs, double myarray[],float result[],bool tempcomp) ; 

then compiler error.