I have done some search about problems when using time.h to obtain a random seed initialization. Particularly in my case, I want to place the time outside the main function.
Based on the comments I made some changes. After including twice in the include as and , these errors and warning went off:
too few arguments to function ‘random’
implicit declaration of function ‘srandom’ [-Wimplicit-function-declaration]
too few arguments to function ‘random’
Once I declared the code as:
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <stdint.h>
#include <unistd.h>
#include <math.h>
int main(void)
{
struct timeval time;
...
}
It works, however it has to move outside main. But if I change to:
#include <sys/time.h>
struct timeval time;
int main(void)
{
...
}
It gives me the error:
‘time’ redeclared as different kind of symbol
In my case the implementation I am working on is in C not in C++. When I try to move the code to a function in order to receive a different random number every time my function is called, some other errors happen:
double myRandom(double dAverage,double dStddev);
double myRandom(double dAverage,double dStddev){
int iRandom1, iRandom2;
double dRandom1, dRandom2,result;
long int liSampleSize;
iRandom1=(random());
dRandom1=(double)iRandom1 /2147483647;
iRandom2=(random());
dRandom2=(double)iRandom2 /2147483647;
result= dAverage + dStddev * sqrt(-2.0 * log(dRandom1))*cos(6.28318531 * dRandom2);
return(result);
}
int main(void){
...
struct timeval time;
gettimeofday(&time, NULL);
srandom((unsigned int) time.tv_usec);
for (i=0; i<liSampleSize;i++)
{ result=myRandom(dAverage,dStddev);
}
}
Apparently it should be working. Has somebody any idea what is wrong here. All comments are highly appreciated.
Update: Then, taking srandom out of myRandom makes the generated values as expected. So, it worked!
