---7.1---

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

#define SIZE  20

struct student {
    char name[11];
    int point;
};

void gen_str(char s[], int n);
void display(struct student x[], int n);

int main(void)
{
    struct student group[SIZE], w;
    int i, j, max;

    for (i = 0; i < SIZE; i++) {
        gen_str(group[i].name, rand() % 5 + 6);
        group[i].point = rand() % 101;
    }
    printf("整列前：\n");
    display(group, SIZE);
    for (i = 0; i < SIZE; i++) {
        max = i;
        for (j = i + 1; j < SIZE; j++)
            if (group[j].point > group[max].point)
                max = j;
        w = group[i]; group[i] = group[max]; group[max] = w;
    }
    printf("整列後：\n");
    display(group, SIZE);
    return EXIT_SUCCESS;
}

void display(struct student x[], int n)
{
    int i;

    for (i = 0; i < n; i++)
        printf("%-15s%4d\n", x[i].name, x[i].point);
}

void gen_str(char s[], int n)
{
    int i;

    for (i = 0; i < n; i++)
        s[i] = rand() % 26 + 'a';
    s[i] = '\0';
}

---7.2---

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

#define SIZE  sizeof(double)

union d_c {
    double d;
    char c[SIZE];
};

void bit_ptn(int c);

int main(void)
{
    union d_c x;
    int i;

    printf("実数を入力して下さい：\n");
    scanf("%lf", &x.d);
    for (i = 0; i < SIZE; i++) {
        bit_ptn(x.c[i]);
        putchar(' ');
    }
    putchar('\n');
    return EXIT_SUCCESS;
}

void bit_ptn(int c)
{
    int i;

    for (i = 7; i >= 0; i--)
        putchar(c & (1 << i) ? '1' : '0');
}