PROBLEM Generate random numbers using rand() in C

[parpik]

Hi everyone! I'm making program where user enters numbers and program will find MAX and MIN + position of these numbers. I want to give the user a choice for the program to fill in the numbers for him using rand(). It's working almost perfect, program will find the MAX number with the position but the problem occurs when printing MIN number with position - always prints number 8 and position 1. Where is the problem? Finding MAX number is working but program cannot find MIN number. Thank you for your help  Here is my code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

typedef struct elementposition
{
    int min;
    int max;
    int positionMax;
    int positionMin;
}elementposition;

int main()
{
    struct elementposition minmax;
    srand(time(NULL));
    int a[500], i;
    int c = sizeof(a) / sizeof(a[0]);
    char y;

    printf("How many numbers you want to enter: ");
    scanf("%d", &c);
    minmax.positionMax=minmax.positionMin = 0;

    printf("Want to fill with random numbers? (Y/N)");
    scanf(" %c",&y);

    if(y == 'Y'||y == 'y')
    {
        for(i = 0; i < c; i++)
        {
            a[i] = rand() % 10000 + 1;

            if(minmax.max < a[i])
            {
                minmax.max = a[i];
                minmax.positionMax = i;
            }

            if(minmax.min > a[i])
            {
                minmax.min = a[i];
                minmax.positionMin = i;
            }
        }

        for(i = 0; i < c; i++)
        {
            printf("Number #%d: %d\n", i + 1, a[i]);
        }
    }
    else
    {

    printf("------------------------------------ \n");

    printf("Enter (%d) numbers: \n", c);
    scanf("%d",&a[0]);
    minmax.max = minmax.min = a[0];

    for(i = 1; i < c; i++)
    {
        scanf("%d", &a[i]);

        if(minmax.max < a[i])
        {
            minmax.max = a[i];
            minmax.positionMax = i;
        }

        if(minmax.min > a[i])
        {
            minmax.min = a[i];
            minmax.positionMin = i;
        }
    }
}
        printf("\nMax number is %d, number position %d. \n", minmax.max, minmax.positionMax+1);
        printf("Min number is %d, number position %d. \n", minmax.min, minmax.positionMin+1);

     printf("------------------------------------ \n");

    getch();
    return 0;
}

 

[Sauron]

You don't initialize your .min value before the random part so whatever is in there when you start the program is what it begins with. If that value is lower than all randomly generated values then the program will never enter the if statement. Just initialize the values to the maximum and minimum int values respectively and the problem is solved.

#include <limits.h>
/*...*/	
int main()
{
  struct elementposition minmax;
  minmax.min = MAX_INT;
  minmax.max = MIN_INT;
/*...*/

 

[wanderingfool2]

The only thing I would like to comment on would be that you should always be careful with arrays and letting the user decide how many to put in.

 

You should be checking c after the user inputs the amount of numbers they wish to put in, because if they write 600, then they are writing an extra 100 ints into memory that is not assigned