srand(time()) returns segmentation fault

Hey everyone,
Here's another problem I encountered:

when I write this: (This is a beginning of a "guess a number game")

Code:

---

#include <stdio.h>

main()
{

  int iRandomNum = 0;
  int iResponse = 0;
  srand(time());

  iRandomNum = (rand() % 10) + 1;

...

---

it returns a segmentation fault. I tested multiple instances, and what I observed is, whenever I define a variable as (rand() % 10) + 1 following srand(time()) it doesn't work and I'm not sure why.

This however works:

Code:

---

#include <stdio.h>

main()
{

  srand(time());

  printf("\n%d\n", (rand() % 8) + 1);
}

---

The first code snippet is provided by the book "C programming for the absolute beginner"

Thanks for all the help

time() has to take a parameter. Read the manual! You can pass it NULL:

Code:

---

srand(time(NULL));

---

Calling it without the parameter is equal to calling it with garbage. So your program crashes.

Thanks brewbuck for the rapid help.

It works!

wait but actually I have another question, how come it works without a NULL in this code?
Thanks again for the help,

Code:

---

#include <stdio.h>

main()
{

  int iRandomNum = 0;
  srand(time());

  iRandomNum = (rand() % 4) + 1;

  printf("\nFortune Cookie-Chapter 3\n");

  switch (iRandomNum) {

  case 1:
    printf("\nYou will meet a new friend today.\n");
    break;
  case 2:
    printf("\nYou will enjoy a long and happy life.\n");
    break;
  case 3:
    printf("\nOpportunity knocks softly. Can you hear it?\n");
    break;
  case 4:
    printf("\nYou'll be financially rewarded for your good deeds.\n");
    break;
  } // end switch
} // end main

---

Quote:

---

Originally Posted by withoutn

wait but actually I have another question, how come it works without a NULL in this code?

---

Random freaking chance. When you play Russian Roulette, 5 times out of 6 you survive.

Hey, it's me again. Sorry for bugging you with all these questions, but I just wrote this, and I get a segmentation fault again.

Code:

---

#include <stdio.h>

main()
{

  int intRandomNum = 0;
  int intResponse = 0;
  srand(time(NULL));

  intRandomNum = (rand() % 10) + 1;

  printf("\n Guess a number between 1 and 10: ");
  scanf("%d", intResponse);

  if (intRandomNum == intResponse)
    printf("\n You got it!\n\n");
  else
    printf("\n Wrong! The correct number is: %d\n\n", intRandomNum);
}

---

Not using scanf() correctly. You need to pass it a pointer to a location to store the result, not the variable itself. Change is made in red below:

Code:

---

#include <stdio.h>

main()
{

  int intRandomNum = 0;
  int intResponse = 0;
  srand(time(NULL));

  intRandomNum = (rand() % 10) + 1;

  printf("\n Guess a number between 1 and 10: ");
  scanf("%d", &intResponse);

  if (intRandomNum == intResponse)
    printf("\n You got it!\n\n");
  else
    printf("\n Wrong! The correct number is: %d\n\n", intRandomNum);
}

---

Oh yes, now it's fine. Thanks for aaaall the help. Sorry for taking up your time :-)

it works because you don't include time.h. If you did, it would give you an error.

Are you getting any warnings with this code?
Are you paying attention to them, or just running the code no matter what?

Since you seem to be using gcc on Linux, then I would suggest
gcc -Werror -W -Wall -ansi -pedantic -O2 prog.c
which would have caught every single problem you've posted so far before you tried to run anything.