prompting user for data

I am a newbie and I want to edit my dice rolling program to prompt the user to input the number of trials and then print the histogram. As it is now, I have the default for the number of times the dice will be rolled set to 1000, but I would rather let the user choose this number. How can I do this? Here is the code from my program:

Code:

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#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define TRIALS 1000
void generate_int(int dice[] ); 
void calc_freq( int dice[],   
        int freq[]);
        void extreme( int *most_freq,   
        int *least_freq,
        int *most_num,
        int *least_num,
        int freq[]);
void print_report ( int freq[],    data
        int *most_freq,
        int *least_freq,
        int *most_num,
        int *least_num,
        FILE *Output);
int main(void)                       
{   
int dice[1000];                       
int freq[10] = {0};
int most_freq =0;
int least_freq =0;
int most_num =0;
int least_num =1001;
FILE *Output;
Output = fopen("out.dat","a");               
srand( time(NULL) );                   
generate_int( dice );                   
calc_freq( dice, freq);
extreme( &most_freq, &least_freq, &most_num, &least_num,freq);
print_report( freq, &most_freq, &least_freq, &most_num, &least_num, Output);
return;                       
}

void generate_int( int dice[] )               
{
int count = 0;
  while( count < TRIALS)
  {
    dice[count] = rand() %10 + 2;
    count++;
  }
}

void calc_freq( int dice[], int freq[] )
{
int count = 0;                               
int temp = 0;
while( count < 1000)
{
  temp = dice[count];
  switch (temp)
    {
    case 2:
        freq[0] = freq[0] + 1;
        break;
    case 3:
        freq[1] = freq[1] + 1;
        break;
    case 4:
        freq[2] = freq[2] + 1;
        break;
    case 5:
        freq[3] = freq[3] + 1;
        break;
    case 6:
        freq[4] = freq[4] + 1;
        break;
    case 7:
        freq[5] = freq[5] + 1;
        break;   
    case 8:
        freq[6] = freq[6] + 1;
        break;
    case 9:
        freq[7] = freq[7] + 1;
        break;
    case 10:
        freq[8] = freq[8] + 1;
        break;
    case 11:
        freq[9] = freq[9] + 1;
        break;
    case 12:
        freq[10] = freq[10] + 1;
        break;
    default:    printf("ERROR: INVALID DATA IN ARRAY DICE[]");
        break;
  }
 count++;
}
}

void extreme( int *most_freq, int *least_freq, int *most_num, int *least_num, int freq[])
{
int count = 0;               

int number = 0;
number = freq[0];
while(count < 11)
{
    if( *most_num < number)
    {   
        *most_num = number;
        *most_freq = count;
    }
    if( *least_num > number)
    {
        *least_num = number;
        *least_freq = count;   
    }   
    count++;
    number = freq[count];
}
}   


void print_report ( int freq[], int *most_freq, int *least_freq, int *most_num, int *least_num, FILE *Output)
{
int number = 0;
int temp = 0;
int starnumber = 0;
int denom = 10;
int count = 0;
int control = 0;
printf("\n\t_______________________________________________________________");
while (count < 11)
{
    temp = count + 2;                                //print data
    starnumber = freq[count]/10;   
    printf("\n\t  Number: %d", temp);
    printf("  Rolled : %d", freq[count]);
    printf("\t    ");
    fprintf(Output,"\n\t  Number: %d", temp);
    fprintf(Output,"  Rolled : %d", freq[count]);
    fprintf(Output,"\t    ");
    while( control <= starnumber)                            //printing stats
    {
        printf("*");
        fprintf(Output,"*");
        control++;
    }
    count++;
    control = 0;
    starnumber = 0;
}
printf("\n\t_______________________________________________________________\n");
number = *most_freq +2;
printf("\t  The most frequent number was: %d ",number);
printf(" occuring %d", *most_num);
printf(" times. \n");
number = *least_freq +2;
printf("\t  The least frequent number was: %d ",number);
printf(" occuring %d", *least_num);
printf(" times. \n");
fprintf(Output,"\n\t_______________________________________________________________\n");
number = *most_freq +2;
fprintf(Output,"\t  The most frequent number was: %d ",number);
fprintf(Output," occuring %d", *most_num);
fprintf(Output," times. \n");
number = *least_freq +2;
fprintf(Output,"\t  The least frequent number was: %d ",number);
fprintf(Output," occuring %d", *least_num);
fprintf(Output," times. \n");
getch();
return;
}

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Use atoi() and fgets(), both defined in stdio.h:

Code:

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#include <stdio.h>
#define BUFSIZE 5

int main(int argc, char * * argv) {
  char buf[BUFSIZE]; //max of five digits
  printf("How many rolls? ");
  fgets(buf, BUFSIZE, stdin);
  int rolls = atoi(buf);
  printf("Number of rolls: %d\n", rolls);
}

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PS, you should look at rewriting a lot of your code. For example, you have 11 lines of the form

Code:

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freq[0] = freq[0] + 1;

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These could be condensed to just one. Remember that an array subscript can be a variable, not just a constant.

Yeah, and

Code:

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    temp = dice[count];
    switch (temp)

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could be

Code:

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switch(dice[count])

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since temp is not used anywhere else. You should also indent your code consistently.

Code:

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int dice[1000];

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Would be better if you used your define:

Code:

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int dice[TRIALS];

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Code:

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int freq[10] = {0};

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There are 11 possible results, not 10.

Code:

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void generate_int( int dice[] )               
{
    int count = 0;
    while( count < TRIALS)
    {
        dice[count] = rand() %10 + 2;
        count++;
    }
}

---

The above generates values in the range from 2 - 11 and not 2 - 12 like you want.

Code:

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while( count < 1000)
{
  temp = dice[count];
  switch (temp)
    {
    case 2:
        freq[0] = freq[0] + 1;
        break;
    case 3:
        freq[1] = freq[1] + 1;
        break;
    case 4:
        freq[2] = freq[2] + 1;
        break;
    case 5:
        freq[3] = freq[3] + 1;
        break;
    case 6:
        freq[4] = freq[4] + 1;
        break;
    case 7:
        freq[5] = freq[5] + 1;
        break;   
    case 8:
        freq[6] = freq[6] + 1;
        break;
    case 9:
        freq[7] = freq[7] + 1;
        break;
    case 10:
        freq[8] = freq[8] + 1;
        break;
    case 11:
        freq[9] = freq[9] + 1;
        break;
    case 12:
        freq[10] = freq[10] + 1;
        break;
    default:    printf("ERROR: INVALID DATA IN ARRAY DICE[]");
        break;
  }
 count++;
}

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Already hinted at, the above can simply be replaced with:

Code:

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while( count < TRIALS )
{
    freq[dice[count]-2]++;
    ++count;
}

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Code:

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dice[count] = rand() %11 + 2;

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This is a "poor" way of simulating 2 six-sided die rolls. Generating the outcome that way gives each number (2 through 12) the same chance of coming up. In reality, things are a bit different. For instance, the only way to get 2 would be if the dice pair was {1, 1}. But to get 7 you could have many more dice pairs {1, 6}, {2, 5}, {3, 4} so you're much more likely to end up with 7 than 2. Your code doesn't account for that.

You're better off with at least doing something like:

Code:

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dice[count] = ((rand() % 6) + 1) + ((rand() % 6) + 1);

or

dice[count] = (rand() % 6) + (rand() % 6) + 2;

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