// for_exp.c
#include <stdio.h>
 
int main(void)
{
    int score[100]={0};
    int student_num = 0;
 
    printf("生徒の数を入力してください: ");
    scanf("%d", &student_num);  // <= 6
    if(student_num <= 0)return -1;  // student_numが0以下だったら、プログラムを終了
 
    for (int i = 0;;) {  // 普通はこんなことしません
        int input_score;
        printf("点数を入力してください: ");
        scanf("%d",&input_score);  // <= 80 70 30 40 90 10
        if (!(0 <= input_score && input_score <= 100)) {
            printf("もう一度");
            continue;
        } 
        score[i++] = input_score;
        if (i >= student_num)break;
    }
 
    for(int i = 0; i < student_num; ++i) {
        printf("score[%d]: %d\n", i, score[i]);
    }
 
    return 0;
}

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Ngo4MCA3MCAzMCA0MCA5MCAxMA==

6
80 70 30 40 90 10