How to generate a random generator in C?

[Ruhi22]

I am trying to use the default random generator in C.
the funcion rand() is fine but when tried 'srand(time(0))' it is giving me the following error:


error C3861: 'time': identifier not found




the code I am tryin it in is as follows:

#include <stdio.h>
#include <stdafx.h>
#include <iostream>
#include <stdlib.h>


int main(void)
{
int i, m, x[100];

printf("\n\nEnt er the length of the array: ");
scanf_s("%d", &m);

for(i=0; i<m; i++) x[i]=0;

for(i=0; i<m; i++) x[i]=srand(time(0)) ;

printf("\n\n");
for(i=0; i<m; i++) printf(" %d", x[i]);
printf("\n\n");
}

[JosAH]

You have to include another header file: <time.h> if you want to use the time() function.

kind regards,

Jos

[Tassos Souris]

Let me tell you one interesting thing about srand

When you call srand again with the same seed value then the exact same sequence of pseudo-random integers in range 0 to RAND_MAX shall be repeated.

I think this may help you in debugging and see what is the behavior of your program under the same conditions.

With respect,

Tassos Souris

[sicarie]

Small notes on style:

If you are using C, you can remove the declaration of the C++ header 'iostream'. That may cause issues later on.

Also, best practice is considered to use 'int main()' and then show a return value at the end of your program that will declare if the program completed successfully or not.

Did using Jos' selection of including time.h fix the error?

[donbock]

1. I suggest the argument to time() be NULL rather than 0.
2. I suggest that you explicitly cast the time() return value to unsigned int.

See below. I have repeated the prototypes for the library functions for your reference, but you should accomplish the same by including the appropriate header files.

/* FYI: prototypes for the standard library functions */
void srand(unsigned int seed);
time_t time(time_t *timer);
 
srand( (unsigned int)time(NULL) );