Thread: conflicting types error question

Originally Posted by failure67

Just skimming your code, so I could be totally wrong, but I imagine you're not meaning to use the XOR operation in line 24.

Why do you say that I use XOR? I am new, so that I may make stupid mistake.

Look at my updated post. You should use a function like pow for what you're trying to accomplish.

Originally Posted by failure67

Look at my updated post. You should use a function like pow for what you're trying to accomplish.

Thanks. I used MATLAB for too long and thought that "^" also mean "to the power" in C.

Originally Posted by iMalc

Don't paraphrase the compiler error messages, copy and paste the exact error messages here.

I don't see pi defined anywhere.

Here is the updated code and the error


C:\Documents and Settings\dcl\Desktop\cprogramming\test1.c|17|error C2371: 'myGaussian' : redefinition; different basic types|
||=== Build finished: 1 errors, 0 warnings ===|

Code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(void)
{
  int i;
  double kk;

  srand(time(NULL));
  i = rand();
  kk = myGaussian(i);
  printf ("Your random number is %f\n", kk);
  return(0);
}

double myGaussian(int x){
    double random_max = 32767; //max int that generate by rand
    double half_random_max = 32767/2;
    double varianece_value = 89481216;  //vairance from 0:32767
    double std_value = 9459.451;    //std from 0:32767
    double temp;
    double pi = 3.14;

    temp = ((1/sqrt(2*pi))*(1/std_value))*exp(-(x-half_random_max)*(x-half_random_max)/(2*varianece_value));
    return temp;

}

Include math.h.
Use M_PI for pi.
Use RAND_MAX for the maximum rand value (it may not be what you assume it is).
Put a prototype of myGaussian before main (or move the whole function there).

Like hk_mp5kpdw said, you need to prototype your myGaussian function. Put the following line above main:

Code:

double myGaussian(int x);

In C, the compiler reads top-down, and doesn't know about anything it hasn't seen yet. You call myGaussian on line 12, but the compiler hasn't seen the function yet, so it doesn't know what parameters it should take and what it should return, so it assumes it returns an int.