Thread: I hate school...

can someone tell me why this doesnt generate anything but 0's.

Code:

void read()
{
 for(suba = 0; suba < 4; suba++)
 {
  for(subb = 0; subb < 8; subb++)
  {
   x = rand()%51;
   if(x > 50 || x < 1)
   {
    num[suba][subb] = x;
    continue;
   }
  printf("%4d", num[suba][subb]);
  }
 printf("\n");
 }
}

there is an array declared above called num[4][8] as well as the other variables.

you if statement is the probelm it should read
if(x < 50 && x > 1)

when you want to have a number in a ceratain range you need to have and instead of or cause if the first part of your or condition is false the if statment will never execute, but if you use and then both condition have to be vaild.

Hope this help you

oh i forgot one more thing when you are using the rand function you have to do following

at the top of your program put

#include <time.h>

and before you call the rand() put

srand(time(NULL));

this will help in generating random numbers, don't ask me why, but it works

one more thing i forgot, take out the continue, it is considered bad programming habit, and you should never use it cause you can write loops such as a for, while or do while that can control your program.

Good Luck

There are comments throught out the following code that you might want to take note of - a lot of them are not to do with your immediate problem, but good to know, nonetheless.

Code:

#include <stdio.h>
#include <stdlib.h> /* need this to use rand() */
#include <time.h>   /* for srand() */

int num[4][8];

int suba = 0;
int subb = 0;
int ctr = 0;
int ctr2 = 0;
int x = 0;

void eoj(void);   /* if function takes no parameters use void */ 
void read(void);
int getrand(int range);

int main(void) /* main returns an int - always */ 
{
    read();
    return 0;  /* should return status to the caller */ 
}

void read(void)
{

    srand(time(NULL));
    for (suba = 0; suba < 4; suba++) {
	for (subb = 0; subb < 8; subb++) {
	    x = getrand(50); /*get random numbers, argument is to set range of numbers */
	    num[suba][subb] = x;
	....}
    }


    printf("\n");

}


void eoj(void)
{
    name();
    printf("EXECUTION COMPLETED... Press ENTER to contiune.\n");
    getchar();
}

 /* getrand will get you numbers between 0 and 50 */ 

int getrand(int range)
{
    return (int) ((double) rand() / ((double) RAND_MAX + 1) * range);
}

You might also try 'man 3 rand' if you are on a *nix computer.

I will leave it up to you to figure out how to properly print all of the elements out.

HTH

~/

That did the trick. Thanks. Now I am stuck on how to get it to do a basic search of the array and print whether or not an integer entered is in the array. It prints every single time it loops, I only want one answer, that the number is in the array or it is not, and then the location (eg num[4][0]). Here is the code so far:

Code:

void diff()
{
 char ans;
 int s;
 printf("\n\nSearch for a number in the array?");
 fflush(stdin);
 scanf("%c", &ans);
 if(ans == 'y' || ans == 'Y')
 {
  printf("\n\nKey in integer to be searched for:");
  fflush(stdin);
  scanf("%d", &s);
  for(suba = 0; suba < 4; suba++)
  {
   for(subb = 0; subb < 8; subb++)
   {
    if(num[suba][subb] == s)
    {
     printf("\n\n%d is in the array\n", s);
     break;
    }
    else
    {
     printf("\n\n%d is not in the array", s);
    }
    if(ans == 'N' || ans == 'n')
    {
     eoj();
    }
   }
  }
 }
}

this will help in generating random numbers, don't ask me why, but it works

The reason why you need this is because rand() will always return the same series of random numbers for a given seed. As such if you do not seed the random number generator (using srand() ) it will use the default value.

edit: Forgot to add: what srand( (unsigned) time(NULL)); does it to get the current time in seconds and use that to seed the RNG. However this is not fool proof as if you run the program in the same second you will get the same results.

ok, that part is working now its the second half I do not get. I have to make a loop that will print if a certain number is in the array, now filled with the random numbers. And only print one answer, that it is not in there, or that it is in there at a certain location

There is a new chunk of code just a couple of post above this one with the new function that I tried out. I just need to get it to break out of two loops instead of one.