Always missing an value while printing outcomes (Problem 20 C)

Hello, everyone!

I find if I use getchar() to solve this problem, I'll always miss the last value while printing outcomes.

I've searched online and thought that would be the stdin buffers remains aftering using scnaf(). However, it just printed nothing when I tried the solutions I searched like fflush(stdin) or while-statment.

Now I really don't know what's the problem here.

Here's my code:

#include <stdio.h>

int scan(char*);

int main(void) {
    int num;
    scanf("%d", &num);

    int cnt[num]={0};
    for (int i=0; i<num; ++i) {
        char str[100];
        int len=scan(str);
        for (int j=0; j<len; ++j) {
            if (*(str+j)=='a' || *(str+j)=='i' || *(str+j)=='u' || *(str+j)=='e' || *(str+j)=='o' || *(str+j)=='y') cnt[i]++;
        }
    }

    for (int i=1; i<num; ++i) printf("%d ", cnt[i]);

    return 0;
}

int scan(char* str) {
    int len=0;
    char c=getchar();
    while (c != '\n') {
        *(str+len) = c;
        len++;
        c=getchar();
    }
    return len;
}

Thanks for your advising. It turns out it's my carelessness of not checking c!=EOF in scan() leads this circumstance. I really learned from this problem.