Input only number C programming

Question

currently i am doing a program to get the input (0 to 50) from the user. If the number is out of the range then the number will not be counted. After that, i will calculate and

Answer 1

like this

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>

int get_int(const char *prompt){
    char buff[32];

    for(;;){
        fputs(prompt, stdout);fflush(stdout);
        if(fgets(buff, sizeof buff, stdin)){
            if(strchr(buff, '\n')){
                char *endp;
                long n;

                errno = 0;
                n = strtol(buff, &endp, 10);
                if(errno == 0 && *endp == '\n' && INT_MIN <= n && n <= INT_MAX)
                    return n;
            } else {//too long input
                while(getchar() != '\n');
            }
        } else {//input EOF
            continue;//ignore EOF
        }
    }
}

int main(void){
    int n = 0, score, min = INT_MAX, max = INT_MIN;
    double total = 0, average;

    printf("Enter test scores,-1 to exit\n");
    while((score = get_int("* Scores[%d] (0-50) : ")) != -1){
        if(score < 0 || score > 50)
            continue;

        total += score;
        if(score > max)
            max = score;
        if(score < min)
            min = score;
        ++n;
    }
    if(n){
        average = total / n;
        printf("Average marks = %.2f\n", average);
        printf("MIN:%d\n", min);
        printf("MAX:%d\n", max);
    } else {
        puts("No valid input");
    }
}

Answer 2

You could choose among options:
A. Take input as string and then verify if the string is number. Else, discard it.
B. Trap key downs. If if is alphabet or symbol, discard. If 0-9, use it.