Putting output from rand() into an array

Question

I wrote a small dice rolling program that will print out the results of however many dice rolls that are entered. I want to count how much each number occurs so I thought I would put the output from the rand() function into an array and then search the array for the different values. I don't know how to put numbers into an array that are not entered in manually.

 #include <stdio.H>
 #include <stdlib.h>
 #include <time.h>
 int main(void)
 {
 int count; 
 int roll; 
 srand(time(NULL));
 printf("How many dice are being rolled?\n");
 scanf("%d", &count);
 printf("\nDice Rolls\n");
 for (roll = 0; roll < count; roll++)
 {
 printf("%d\n", rand() % 6 + 1);
 }
 return 0;
 }

• autistic: Oh, goody! A new user. There is no <stdio.H>. I think you meant <stdio.h>. Which book are you reading?
• user2209482: Yeah, that was a typo. I have the Absolute Beginner's Guide to C, second edition by Greg Perry and C Primer Plus, fifth edition by Stephen Prata.

Answer 1

 #include <stdio.H>
 #include <stdlib.h>
 #include <time.h>
 int main(void)
 {
 int count; 
 int roll; 
 int* history;
 srand(time(NULL));
 printf("How many dice are being rolled?\n");
 scanf("%d", &count);
 history = malloc( sizeof(int) * count );
 if( !history )
 {
 printf( "cannot handle that many dice!\n" );
 exit( -1 );
 }
 printf("\nDice Rolls\n");
 for (roll = 0; roll < count; roll++)
 {
 history[roll] = rand() % 6 + 1;
 printf("%d\n", history[roll]);
 }
 // do something interesting with the history here
 free( history );
 return 0;
 }

• Elazar: if you add check for allocation failure, why not add a check for bad scanf too.
• K Scott Piel: Because it was not my intent to show him how to use scanf, it was to show him how to correctly allocate and use a dynamic array? ~smile~

Answer 2

just put it into the array

for (roll = 0; roll < count; roll++)
{
 myArray[roll] = rand() % 6 + 1;
 printf("%d\n", myArray[roll] );
}

• K Scott Piel: Bear in mind that your solution here does not take into account the fact that the user is inputting a variable number of die to roll, not specifically three die.

Answer 3

If you want to track the number of occurences of each result, you don't even need to save every dice roll.

int result[6] = {} ; // Initialize array of 6 int elements
int current = 0; // holds current random number
for (roll = 0; roll < count
{
 current = rand() % 6;
 result[current]++; // adds one to result[n] of the current random number
 printf("%d\n", current+1);
}

After which you will have an array 0-5 (result), with each element containing the number of each occurence (you will need to add the element number + 1 to get the actual roll). ie. result[0] is the number of occurences of '1'.

• Jon H. C: Why, thank you. And yes, that is correct twalberg so thanks for that correction as well.