Finding max, min, and avg of student grades in array [c]

Question

Hihi, everyone. Please take a look at my coding and help me fix two things.

First, my 'try again' part is supposed to go back to the original student number count instead of moving to a next student. I think I'm using the loop wrong, but not sure how to fix it. I tried putting the loop outside of my 'for (i=1;i<11;i++)', but it didn't work.

Second, my min and avg work fine, but not max. It keeps giving me a random number and I don't know why.

Thank you so much.

#include<stdio.h>

void main() {

int i,a[10],max=a[0],min=a[0],avg,sum=0;

    printf("please input student score one at a time.\n");

    for (i=1;i<11;i++) {

        printf("Student %d : ",i);
        scanf("%d",&a[i]);

            while (a[i] > 100 || a[i] < 0) {

                printf("Try again!\n");
                i-1//im trying to keep the same student count after 'try again'
                break;
            }

        if (max < a[i]) max = a[i];
        if (min > a[i]) min = a[i];
        sum+=a[i];

    }

avg=sum/10;

printf("\n***************final result ***************\n");
printf("                The maximum score is %d\n",max);//only my max is broken. min & avg works fine
printf("                The minimum score is %d\n",min);
printf("                The average score is %d",avg);

getch();

}

Answer 1

Pleas try this

#include <stdio.h>

int main() {

    int i = 0;
    int a[10];
    int max = -1;
    int min = 101;
    int avg = 0;
    int sum = 0;

    printf("please input student score one at a time.\n");

    while(i < 10) {
        printf("Student %d : ",i);
        scanf("%d", &a[i]);
        if(a[i] > 100 || a[i] < 0) {
            printf("Try again!\n");
            continue;
        }

        if (max < a[i]) max = a[i];
        if (min > a[i]) min = a[i];
        sum += a[i];

        i++;
    }

    avg = sum/10;

    printf("\n***************final result ***************\n");
    printf("                The maximum score is %d\n",max);//only my max is broken. min & avg works fine
    printf("                The minimum score is %d\n",min);
    printf("                The average score is %d",avg);

    return 0;
}

Answer 2

Looks like homework, so I will just provide hints to how you can solve your issue

1. Instead of decrementing the counter, just place a printf and scanf in the while loop till it finally satisfies the conditions.
2. You are getting a random number because you are assigning max and min to a[0] right after declaring the array a[10], and you have not initialized any values in the array. In C, the memory location where the computer assigns space for the array might not necessarily be empty. Thus, your max gets a random value in it from the start. This could happen to min too, just that in your case it happened to max. One way to solve this is to initialize the whole array. Another way is just to assign the integer 0 to max and the integer 100 to min, since it will never go below 0 or above 100.

Hope this helps, all the best with your problem.

Answer 3

#include<stdio.h>

void main() {

int i,a[10],max=a[0],min=a[0],avg,sum=0;

printf("please input student score one at a time.\n");

for (i=1;i<11;i++) {

    printf("Student %d : ",i);
    scanf("%d",&a[i]);

        if (a[i] > 100 || a[i] < 0) {

            printf("Try again!\n");
            i--;
            continue;
        }

    if (max < a[i]) max = a[i];
    if (min > a[i]) min = a[i];
    sum+=a[i];

}

avg=sum/10;

printf("\n***************final result ***************\n");
printf("                The maximum score is %d\n",max);
printf("                The minimum score is %d\n",min);
printf("                The average score is %d",avg);


}

test in this site

Answer 4

Thank you everyone for all your help. My code looks better now. I took out '=[0]' from both min and max and changed 'while' to 'if' with --i. Please let me know if I need to change more.

#include<stdio.h>

void main() {

int i,a[10],max,min,avg,sum=0;

    printf("please input student score one at a time.\n");

    for (i=1;i<11;i++) {

        printf("Student %d : ",i);
        scanf("%d",&a[i]);

        if (a[i] > 100 || a[i] < 0) {

            printf("Try again!\n");
            --i;
            continue;
        }

        if (max < a[i]) max = a[i];
        if (min > a[i]) min = a[i];
        sum+=a[i];

    }

avg=sum/10;

printf("\n***************final result ***************\n");
printf("                The maximum score is %d\n",max);
printf("                The minimum score is %d\n",min);
printf("                The average score is %d",avg);

getch();

}